APPARATUS AND METHODS FOR OPTIMIZING DIRECT GAS OPERATED FIREARMS

Description

PRIORITY

This application claims the benefit of and priority to U.S. Provisional Application, entitled “Apparatus And Methods For Optimizing Direct Gas Operated Firearms,” filed on Dec. 1, 2023, and having application Ser. No. 63/605,126, the entirety of said application being incorporated herein by reference.

FIELD

Embodiments of the present disclosure generally relate to firearms. More specifically, embodiments of the disclosure relate to an apparatus and methods for an optimized direct gas operated firearm.

BACKGROUND

The AR15/M4/M16 family of firearms and their derivatives, including all direct gas operated versions, have been in use by the military and civilian population for many years. An essential component of direct gas operated firearms is the bolt carrier group. Typically, the bolt carrier group includes a bolt mounted in a bolt carrier that is configured for axial sliding movement and rotation within a firearm. A firing pin is slidably mounted within the bolt and bolt carrier. The bolt carrier group further includes a cam-pin that limits rotation between the bolt and the bolt carrier.

The bolt carrier group generally is configured for stripping or picking up ammunition cartridges from a magazine and moving the cartridges into a battery position within a breech of the firearm. After firing each round, the bolt carrier group extracts and ejects the ammunition cartridge through an ejection port on a side of the firearm. The energy to perform these functions is provided by way of hot, expanding gases from the fired cartridge that are directed through a port at the end of the barrel and channeled back to the bolt carrier group. The expanding gases strike, or impinge, the bolt carrier moving it rearward toward the buttstock and into a retracted position. The exhaust gases are then discharged through the ejection port on the side of the firearm. After discharge, a spring acting on the bolt carrier group moves the bolt carrier back to an engaged position while at the same time stripping another cartridge from the magazine and moving that cartridge into the battery position.

Given the popularity of the AR15/M4/M16 family of firearms and their derivatives, there is a continuing desire to improve and simplify the operation of such direct gas operated firearms. Embodiments presented herein provide for optimizing various aspects and increasing the longevity of a direct gas operated rifle.

SUMMARY

Apparatuses and methods are provided for an optimized direct gas operated firearm. The firearm includes an upper receiver coupled with a lower receiver by a tensioning screw that reduces wobble between the upper and lower receivers. A barrel extension is configured to eliminate misalignment during installation into the upper receiver. A bolt carrier includes a reinforced bolt assembly and a forward-biased dwell weight. The bolt assembly includes an extractor and an extractor pin that simplify disassembly of the firearm. A handguard includes locks that attach to a barrel nut area of the firearm. The locks clamp onto the barrel nut area to align the handguard with the upper receiver. An ambidextrous bolt catch release assembly is operable from either side of the lower receiver. A bolt catch release paddle is disposed at the front of a trigger guard to provide easy access from either side of the lower receiver.

In an exemplary embodiment, an apparatus for a direct gas operated firearm, comprises: an upper receiver coupled with a lower receiver by a tensioning screw; a bolt carrier for moving longitudinally within the upper receiver; a bolt assembly comprising the bolt carrier; a barrel extension for avoiding misalignment during installation into the upper receiver; a handguard that attaches to a barrel nut area of the firearm; and an ambidextrous bolt catch release assembly.

In another exemplary embodiment, the bolt carrier comprises: a cylindrical member for moving longitudinally within the upper receiver; a distal end for supporting a bolt; a proximal end for moving within a receiver extension; and a forward-biased dwell weight within the proximal end. In another exemplary embodiment, the forward-biased dwell weight comprises: a sealed cylinder configured to slide within a cylindrical interior of the bolt carrier; a spring biasing the cylinder in a forward disposition within the interior of the bolt carrier; and a threaded plug that encloses a proximal end of the bolt carrier.

In another exemplary embodiment, the bolt assembly comprises: a bolt comprising a cylindrical member having a forward recess surrounded by multiple lugs and a side recess; an extractor pivotally mounted in the side recess by way of an extractor pin; a claw portion of the extractor biased into the forward recess by one or more springs acting on the extractor; and an ejector and a spring disposed in the forward recess. In another exemplary embodiment, the extractor pin comprises: an elongated member including a center portion configured to seat within holes in parallel prongs of the extractor pin; a first end portion and a second end portion both configured to seat within transverse holes disposed in the bolt assembly; and a bevel joining the center portion with each of the first end portion and the second end portion.

In another exemplary embodiment, the upper receiver comprises: an unthreaded boss including a barrel tenon portion at a front of the upper receiver; an ejection channel disposed on a first side of the upper receiver; a cam strike face disposed on a second side of the upper receiver; and a reinforced wall portion adjacent to the barrel tenon portion. In another exemplary embodiment, the ejection channel is positioned forward of an ejection port of the upper receiver and is configured to accommodate an increase in operational speed of the firearm due to wear. In another exemplary embodiment, the ejection channel is configured to direct ejected shells away from bouncing back into the ejection port and jamming the firearm.

In another exemplary embodiment, the barrel extension comprises: a cylindrical middle section for installation inside a barrel tenon portion of the upper receiver; a short ring disposed at a first end of the cylindrical middle section; a flange disposed at a second end of the cylindrical middle section; and a front surface of the flange for contacting a front surface of the upper receiver. In another exemplary embodiment, the short ring is configured to be centered within the upper receiver when the front surface of the flange is squarely fitted against the front surface of the upper receiver. In another exemplary embodiment, the short ring has a diameter that is slightly larger than the diameter of the cylindrical middle section. In another exemplary embodiment, the cylindrical middle section is adapted to receive an adhesive after the short ring and the front surface of the flange have been zero-fitted into the upper receiver.

In another exemplary embodiment, the handguard comprises: an elongated cylinder having a distal end and a proximal end; an opening extending through the handguard; and a lock assembly for attaching the handguard to a barrel nut area of the firearm. In another exemplary embodiment, the lock assembly includes locks that are threadably engaged with opposite ends of a drive screw. In another exemplary embodiment, the locks are configured to clamp onto the barrel nut area such that the handguard is pushed rearward toward a front surface of the upper receiver so as to align the handguard with the upper receiver.

In another exemplary embodiment, the ambidextrous bolt catch release assembly comprises: a bolt catch release paddle that is configured to be operated from either side of the lower receiver; a bolt catch shaft and a spring that extend from the bolt catch release paddle to a bolt catch; and an auxiliary bolt catch release paddle. In another exemplary embodiment, the bolt catch release paddle is disposed at the front of a trigger guard to provide easy access from either side of the lower receiver. In another exemplary embodiment, the bolt catch shaft and the spring extend vertically through the lower receiver. In another exemplary embodiment, a vertical hole in the upper receiver is configured to slidably house the bolt catch shaft and the spring.

In another exemplary embodiment, the tensioning screw comprises: a threaded portion for engaging a threaded hole in the lower receiver; a head portion for contacting a rear lower lug of the upper receiver; an upper shaped opening disposed in the head portion; and a lower shaped opening disposed in a bottom end of the threaded portion.

These and other features of the concepts provided herein may be better understood with reference to the drawings, description, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings refer to embodiments of the present disclosure in which:

FIG. 1 illustrates a right-side elevation view of an exemplary embodiment of a firearm that utilizes direct gas impingement to operate a bolt carrier group comprising the firearm, in accordance with the present disclosure;

FIG. 2 illustrates a left-hand side view of an exemplary embodiment of a bolt carrier in accordance with the present disclosure;

FIG. 3 illustrates an exploded view of an exemplary embodiment of a forward-biased dwell weight comprising a bolt carrier, according to the present disclosure;

FIG. 4 illustrates a close-up view a proximal end of the bolt carrier of FIG. 2, according to the present disclosure;

FIG. 5 illustrates a cross-sectional view of the bolt carrier of FIG. 4, taken along a line 5-5, according to the present disclosure;

FIG. 6 illustrates a right-hand side view of an exemplary embodiment of a bolt carrier in accordance with the present disclosure;

FIG. 7 illustrates a top view of a distal end of the bolt carrier of FIG. 2, showing a cam pin locking path, in accordance with the present disclosure;

FIG. 8 illustrates a ghost-view of a bolt carrier that includes an exemplary embodiment of a forward-biased dwell weight in accordance with the present disclosure;

FIG. 9 illustrates a midline cross-sectional view of the bolt carrier of FIG. 8, according to the present disclosure;

FIG. 10 illustrates a close-up view of an exemplary embodiment of a forward-biased dwell weight comprising a bolt carrier in accordance with the present disclosure;

FIG. 11 illustrates an isometric view of an exemplary embodiment of a bolt assembly that is suitable for implementation of a cartridge extractor, according to the present disclosure;

FIG. 12 illustrates a cross-sectional view of the bolt assembly shown in FIG. 11;

FIG. 13 illustrates an upper isometric view of an exemplary embodiment of an extractor in accordance with the present disclosure;

FIG. 14 illustrates a lower isometric view of an exemplary embodiment of an extractor in accordance with the present disclosure;

FIG. 15 illustrates a top view of an exemplary embodiment of an extractor in accordance with the present disclosure;

FIG. 16 illustrates a bottom view of an exemplary embodiment of an extractor in accordance with the present disclosure;

FIG. 17 illustrates a cross-sectional view of the extractor shown in FIG. 16, taken along line 17-17, in accordance with the present disclosure;

FIG. 18 illustrates a first side view of an exemplary embodiment of a bolt, according to the present disclosure;

FIG. 19 illustrates a second side view of the bolt shown in FIG. 18, according to the present disclosure;

FIG. 20 illustrates a front view of the bolt shown in FIG. 18, in accordance with the present disclosure;

FIG. 21 illustrates an isometric view of an exemplary embodiment of an extractor pin that may be coupled with an extractor and bolt, in accordance with the present disclosure;

FIG. 22 illustrates a close-up view of a side of an exemplary embodiment of a cartridge extractor pin coupled with a bolt assembly in accordance with the present disclosure;

FIG. 23 illustrates a ghost view of the cartridge extractor pin and the bolt assembly shown in FIG. 22, according to the present disclosure;

FIG. 24 illustrates a lower isometric view of an exemplary embodiment of an extractor pin coupled with an exemplary embodiment of an extractor in accordance with the present disclosure;

FIG. 25 illustrates a bottom view ghost view of the extractor pin and the extractor shown in FIG. 24, according to the present disclosure;

FIG. 27 illustrates an upper isometric view of an exemplary embodiment of an upper receiver configured for use in a direct gas impingement operated firearm, according to the present disclosure;

FIG. 28 illustrates a lower isometric of an exemplary embodiment of an upper receiver configured for use in a direct gas impingement operated firearm, in accordance with the present disclosure;

FIG. 29 illustrates a right-hand side view of the exemplary embodiment of the upper receiver shown in FIGS. 27-28, according to the present disclosure;

FIG. 30 illustrates a left-hand side view of the exemplary embodiment of the upper receiver of FIGS. 27-28, according to the present disclosure;

FIG. 31 illustrates an isometric view of an exemplary embodiment of a barrel extension that is configured to avoid misalignment during installation into an upper receiver, in accordance with the present disclosure;

FIG. 32 illustrates a cross-sectional isometric view of an exemplary embodiment of a barrel extension that is configured to avoid misalignment during installation into an upper receiver in accordance with the present disclosure;

FIG. 33 is a cross-sectional isometric view of an exemplary embodiment of a barrel extension that is coupled with a barrel tenon portion of an upper receiver, according to the present disclosure;

FIG. 34 illustrates a rearward isometric view of an exemplary embodiment of a handguard that may be incorporated into the firearm of FIG. 1, according to the present disclosure;

FIG. 35 illustrates a forward isometric view of an exemplary embodiment of a handguard that may be incorporated into the firearm of FIG. 1, according to the present disclosure;

FIG. 36 illustrates a cross-sectional view of a proximal end of an exemplary embodiment of a handguard, taken along a midline of the handguard, according to the present disclosure;

FIG. 37 illustrates a cross-sectional view of the handguard of FIG. 36, taken along a line 37-37 in accordance with the present disclosure;

FIG. 38 illustrates an isometric view of an exemplary embodiment of a lock assembly that may be used to attach to the handguard of FIG. 34 to the firearm of FIG. 1, according to the present disclosure;

FIG. 39 illustrates a cross-sectional view of the lock assembly of FIG. 38, taken along a midline of the lock assembly in accordance with the present disclosure;

FIG. 40 illustrates an isometric view of an exemplary embodiment of a drive screw that may be implemented in the lock assembly of FIG. 39, in accordance with the present disclosure;

FIG. 41 illustrates a ghost-view of an exemplary embodiment of a lower receiver that includes an ambidextrous bolt catch release assembly according to the present disclosure;

FIG. 42 illustrates a cross-sectional view of the lower receiver of FIG. 41, taken along line 42-42, in accordance with the present disclosure;

FIG. 43 illustrates a cross-sectional view of the lower receiver of FIG. 41, taken along a line 43-43 of FIG. 42, according to the present disclosure;

FIG. 44 illustrates an isometric view of an exemplary embodiment of an ambidextrous bolt catch release assembly in absence of a lower receiver, according to the present disclosure;

FIG. 45 illustrates an exploded view of the ambidextrous bolt catch release assembly of FIG. 44, in accordance with the present disclosure;

FIG. 46 illustrates a cross-sectional view of the firearm of FIG. 1, showing an exemplary embodiment of a tensioning screw coupled between an upper receiver and a lower receiver comprising the firearm, according to the present disclosure;

FIG. 47 illustrates an upper isometric view of an exemplary embodiment of a tensioning screw for reducing wobble between the upper and lower receivers of the firearm, according to the present disclosure;

FIG. 48 illustrates a lower isometric view of an exemplary embodiment of a tensioning screw for reducing wobble between the upper and lower receivers of the firearm, according to the present disclosure;

FIG. 49 illustrates a top view of an exemplary embodiment of a tensioning screw disposed in a lower receiver, according to the present disclosure; and

FIG. 50 illustrates a bottom view of an exemplary embodiment of a tensioning screw disposed in a lower receiver, in accordance with the present disclosure.

While the present disclosure is subject to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. The present disclosure should be understood to not be limited to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one of ordinary skill in the art that the optimized direct gas operated firearm and methods disclosed herein may be practiced without these specific details. In other instances, specific numeric references such as “first screw,” may be made. However, the specific numeric reference should not be interpreted as a literal sequential order but rather interpreted that the “first screw” is different than a “second screw.” Thus, the specific details set forth are merely exemplary. The specific details may be varied from and still be contemplated to be within the spirit and scope of the present disclosure. The term “coupled” is defined as meaning connected either directly to the component or indirectly to the component through another component. Further, as used herein, the terms “about,” “approximately,” or “substantially” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein.

The AR15/M4/M16 family of firearms and their derivatives, including all direct gas operated versions, have been in use by the military and civilian population for many years. Given the popularity of the AR15/M4/M16 family of firearms and their derivatives, there is a continuing desire to improve and simplify the operation of such direct gas operated firearms. Embodiments presented herein provide for optimizing various aspects and increasing the longevity of a direct gas operated rifle.

FIG. 1 illustrates a right-side elevation view of an exemplary embodiment of an optimized direct gas operated firearm 100 (hereinafter, “firearm 100”) that utilizes direct gas impingement to cycle the action of a bolt carrier group comprising the firearm, as described herein. The firearm 100 is a member of the AR15/M4/M16 family of firearms, and thus the firearm 100 includes an upper receiver 104 that houses the bolt carrier group and a lower receiver 108 that receives a magazine 112 containing a multiplicity of ammunition cartridges. The lower receiver 108 positions the ammunition cartridges within the upper receiver 104 such that the bolt carrier group can strip cartridges into a battery position within a breech of a barrel 116. An ejection port 120 on a side of the upper receiver 104 enables the bolt carrier group to eject spent ammunition cartridges after each round is fired. A receiver extension 124 coupled with a rear of the upper receiver 104 provides a housing for longitudinal movement of the bolt carrier group during stripping and ejecting ammunition cartridges. A buttstock 128, a handguard 132, and a grip 136 facilitate a practitioner holding and supporting the firearm 100 during operating the firearm 100 by way of a trigger 140. Further, a suppressor (not shown) may be coupled with a muzzle end of the barrel 116 to reduce noise and muzzle flash during operating the firearm 100.

As described herein, the bolt carrier group moves longitudinally within the upper receiver 104 during stripping ammunition cartridges from the magazine 112, chambering the cartridges in the breech, and ejecting spent cartridges. The energy to perform these functions is provided by way of hot, expanding gases from each fired cartridge that cause the bolt carrier to move rearward within the receiver extension 124 toward the buttstock 128. The expanding gases are directed to the bolt carrier group from a port at an end of the barrel 116 by way of a gas block 148 and a gas tube (not shown) housed inside the handguard 132. The expanding gases cause the bolt carrier group to move rearward within the receiver extension 124 and then are discharged through the ejection port 120. After discharge, a spring acting on the bolt carrier group moves the bolt carrier forward to an engaged position while at the same time stripping another ammunition cartridge from the magazine 112 and moving that cartridge into the battery position.

FIG. 2 illustrates an exemplary embodiment of bolt carrier 144 that is configured to move longitudinally within the upper receiver 104 during stripping ammunition cartridges from the magazine 112, chambering the cartridges in the breech, and ejecting spent cartridges. The bolt carrier 144 is a generally cylindrical member supporting a bolt 150 at a distal end 152 and having a boss 154, flutes 158, and a beveled ring 162 disposed at a proximal end 156. The boss 154 and the beveled ring 162 are configured to reduce an allowable pitch of the bolt carrier 144 when in a battery position. The bolt carrier 144, the boss 154, and the ring 162 have different diameters that cooperate to cause the bolt carrier 144 to seat advantageously in various positions within the receiver extension 124 (see FIG. 1). Further, the boss 154 provides a tighter fit between the proximal end 156 of the bolt carrier 144 and an inner diameter of the receiver extension 124 that reduces tilt of the bolt carrier 144 when in the battery position. The flutes 158 are configured to allow air transfer into and out of the space between the proximal end 156 and the receiver extension 124 to prevent air pressure from hindering the reciprocating motion of the bolt carrier 144.

FIG. 3 illustrates an exploded view of an exemplary embodiment of a forward-biased dwell weight 160 that may be incorporated into the bolt carrier 144, according to the present disclosure. The forward-biased dwell weight 160 is configured to provide a more efficient use of kinetic energy in the bolt carrier 144 for reliable cartridge extraction without increasing peak carrier group velocity. As will be appreciated, during the powering cycle, work is performed by expanding gas to accelerate the bolt carrier 144. As the bolt carrier 144 accelerates, both the bolt carrier 144 and the forward-biased dwell weight 160 accumulate kinetic energy. After the powering cycle is complete (i.e., no more meaningful gas work is being performed), the bolt carrier 144 and forward-biased dwell weight 160 both have achieved peak velocity and rearward momentum. At this point, the extraction cycle begins. The bolt carrier 144 begins to lose kinetic energy due to frictional losses from cartridge extraction as well as spring force resistance from the recoil spring and hammer spring. The forward-biased dwell weight 160 continues rearward, unimpeded by these forces, and begins to transfer some of its kinetic energy back to the bolt carrier 144 through the spring 168 (see FIG. 3) and/or directly to the bolt carrier 144 upon impact with the threaded plug 172 at the proximal end 156 of the bolt carrier 144. Thus, the forward-biased dwell weight 160 prolongs overall cycle time (i.e., adds “dwell”), which benefits reliability in reducing mechanical wear and providing ample time for the magazine 112 to present the next cartridge for feeding even in adverse environmental conditions.

As shown in FIG. 3, the forward-biased dwell weight 160 comprises a sealed cylinder 164 with a spring 168 and a threaded plug 172. The cylinder 164 is configured to slide within a cylindrical interior 180 of the bolt carrier 144. The mass of the cylinder 164 provides the inertia effect mentioned above. As best shown in FIGS. 8-10, cylindrical guides 184 incorporated into opposite ends of the cylinder 164 are configured to slidably contact the interior 180 of the bolt carrier 144. The cylindrical guides 184 have a slightly larger diameter than the rest of the cylinder 164 such that only the cylindrical guides 184 contact the interior 180 of the bolt carrier 144. Thus, the cylinder 164 is configured to move forward and rearward within the bolt carrier 144 with minimal friction.

The spring 168 is disposed between the threaded plug 172 and a central hole 188 disposed in the cylinder 164. As best shown in FIG. 5, the spring 168 biases the cylinder 164 is a forward disposition within the interior 180 of the bolt carrier 144. In the illustrated embodiment, the forward disposition gives rise to a distance 192 (see FIG. 10) between the cylinder 164 and the threaded plug 172. The distance 192 is proportional to an increase in rebound time (i.e., “rear dwell”) imparted to the bolt carrier 144. As such, the distance 192, as well as the mass of the cylinder 164 and the spring force of the spring 168, may be tuned to produce a desired dwell of the bolt carrier 144. Further, the central hole 188 includes a narrow portion 196 configured to allow airflow in and out of the space between the cylinder 164 and the threaded plug 172. As such, the narrow portion 196 of the central hole 188 prevents air pressure between the cylinder 164 and the threaded plug 172 from hindering the longitudinal movement of the cylinder 164.

Turing, again, to FIG. 3, the threaded plug 172 is a generally disc-shaped member having a diameter and peripheral threads 200 suitable for engaging with threads comprising a threaded portion 204 of the interior 180 of the bolt carrier 144. The threaded plug 172 includes a shaped opening 208 configured to receive a suitable tool for driving the threaded plug 172 into the threaded portion 204. Further, the threaded plug 172 includes a through hole 212 that can be aligned with holes 216 disposed in the threaded portion 204 of the bolt carrier 144. Thus, when the threaded plug 172 is advantageously engaged with the threaded portion 204, such that the through hole 212 aligns with the holes 216, the pin 176 may be pressed through the holes 216 and across the threaded plug 172. As such, the pin 176 serves to prevent the threaded plug 172 from loosening within the threaded portion 204 over time.

As mentioned hereinabove, the forward-biased dwell weight 160 provides an inertial effect when the bolt carrier 144 bottoms out at the end of its stroke, at which point the cylinder 164 continues on and thus introduces a pause before the bolt carrier 144 begins to move forward again. In some embodiments, the forward-biased dwell weight 160 may slow down the very first part of unlocking the bolt 150, which has been observed to be beneficial, in some embodiments. Further, the forward-biased dwell weight 160 is configured to prevent the bolt carrier 144 from bottoming out on a barrel extension 560 (see FIGS. 31-32) comprising the firearm 100 during forward movement. In some embodiments, an elastomer may be disposed on a front surface 220 (see FIGS. 8-10) of cylinder 164 to prolong momentum transfer between the forward-biased dwell weight 160 and the bolt carrier 144, thereby staggering total momentum transfer between bolt carrier 144 and the barrel extension 560 and reducing overall restitution of the bolt carrier group upon impact with the barrel extension 560, commonly known as “bolt bounce.”

FIG. 4 illustrates a close-up view the proximal end 156 of the bolt carrier 144, according to the present disclosure. As described hereinabove, the proximal end 156 includes a boss 154, flutes 158, and a beveled ring 162. The boss 154 and the beveled ring 162 are configured to reduce an allowable pitch of the bolt carrier 144 when in a battery position. As best shown in FIG. 5, the bolt carrier 144 and the boss 154 have different diameters. The diameter of the boss 154 is configured to cause the bolt carrier 144 to seat advantageously in various positions within the receiver extension 124 (see FIG. 1). More specifically, the boss 154 provides a relatively low clearance fit between the proximal end 156 of the bolt carrier 144 and an inner diameter of the receiver extension 124. The low clearance fit reduces the tilt of the bolt carrier 144 when in the battery position. The flutes 158 are configured to allow air transfer into and out of the space between proximal end 156 and the receiver extension 124 to prevent air pressure from hindering the reciprocating motion of the bolt carrier 144.

FIG. 6 illustrates a right-hand side view of the bolt carrier 144. The illustrated embodiment of bolt carrier 144 is configured to operate with a forward assist 224 comprising the firearm 100 shown in FIG. 1. The illustrated embodiment of the forward assist 224 is positioned farther forward along the firearm 100 than the forward assists of conventional firearms. The forward position of the forward assist 224 is configured to optimize the ergonomics of the firearm 100. As will be appreciated by those skilled in the art, the position of the forward assist 224 reduces the number of forward assist notches 228 that must be machined into the bolt carrier 144, as shown in FIG. 6.

FIG. 7 illustrates an exemplary embodiment of a cam pin locking path 232. The cam pin locking path 232 is configured to reduce stresses on lugs 236 comprising the bolt 150 by improving the unlocking cam path as compared with conventional firearms. The cam pin locking path 232 is derived by way of a cycloid-derived unlocking path (e.g., a “curve”) instead of a helical-derived path or a polynomial-derived path typically used in conventional firearms. Analysis has demonstrated that a cycloid unlocking path provides about a 50% decrease in peak rotational acceleration of the bolt 150 as compared to a polynomial-derived path that drives the cam path in conventional firearms. Thus, the cycloid unlocking path increases continuity of cam pin to cam path contact, thereby reducing contact stress of the interaction and reducing peak bending loads on the bolt locking lugs due to frictional forces resisting bolt 150 rotation.

FIG. 11 illustrates an exemplary embodiment of an exemplary embodiment of a bolt assembly 252 that is configured to chamber, fire, and extract spent ammunition cartridges during operation of the firearm 100. The bolt assembly 252 comprises a bolt 256 and an exemplary embodiment of an extractor 260. The bolt 256 is a generally cylindrical member having a forward recess 264 surrounded by multiple lugs 268, and a side recess 272. The recess 264 is configured to engage with a rim of an ammunition cartridge, while the lugs 268 are configured to engage with barrel extension lugs 274 (see FIG. 33). The lugs 268 and the barrel extension lugs 274 cooperate to keep the ammunition cartridge in battery during firing the ammunition cartridge.

As shown in FIG. 12, the side recess 272 is configured to house an extractor 260. The exemplary extractor 260 includes a claw portion 276 and a biased portion 280 that share an intervening pivot portion 284. The claw portion 276 is configured to grip the rim of the ammunition cartridge such that when the lugs 268 unlock from the barrel extension lugs 274 and the bolt assembly 252 moves rearward, the claw portion 276 pulls the ammunition cartridge out of the firing chamber. The biased portion 280 is configured to be biased away from the bolt 256 by way of springs disposed between the biased portion 280 and the bolt 256. In the illustrated embodiment of FIG. 12, the bolt assembly 252 includes a primary spring 288 and a secondary spring 292 that presses the biased portion 280 away from the body of the bolt 256.

The pivot portion 284 serves to press the claw portion 276 into the forward recess 264 due to the forces acting on the biased portion 280 by the springs 288, 292. The pivot portion 284 includes an extractor pin 296 that causes the extractor 260 to move in a seesaw manner during engaging an unfired ammunition cartridge. As such, the pivot portion 284 and the springs 288, 292 allow the claw portion 276 to move over the rim of the cartridge and then cause the claw portion 276 to remain fixedly engaged with the rim of the cartridge until the bolt assembly 252 is withdrawn from the breech of the firing chamber. Further, in some embodiments, the primary spring 288 may comprise a “wave spring” configured to keep the extractor 260 centered within the side recess 272 and thus reduce wear on the bolt assembly 252. As shown in FIGS. 11-12, the bolt assembly 252 further includes an ejector 300 and a spring (not shown) that are configured to throw the cartridge free of the firearm 100 once the cartridge is pulled out of the firing chamber.

FIGS. 13-17 illustrate an exemplary embodiment of an extractor 320 that may be incorporated into the bolt assembly 252 of FIGS. 11-12, in accordance with the present disclosure. Extractor 320 comprises an elongated body 324 that includes a claw portion 328 and a biased portion 332 that share an intervening pivot portion 336. As shown in FIGS. 13 and 15, the extractor 320 includes an upper surface 338 that is rounded or curved in a circumferential direction so as to substantially match a curvature of an exterior surface of the bolt 256 (see FIG. 11). The extractor 320 further includes a lug 342 that extends along the upper surface 338 above the claw portion 328. As shown in FIG. 17, the lug 342 comprises a thicker portion of the extractor 320 that is configured to reinforce the claw portion 328 so as to discourage damage or misalignment of the claw portion 328 that may otherwise arise due to rough handling of the firearm 100, dirt or debris, or by firing a cartridge that is too powerful for the firearm 100. Further details regarding reinforcing the extractor 320 by way of the lug 342, as well as with one or more elongated ribs, can be found in U.S. patent application, entitled “Reinforced Cartridge Extractor For Reciprocating Firearm,” filed on Sep. 20, 2024, and having application Ser. No. 18/891,404, the entirety of said application being incorporated herein by reference.

In general, the claw portion 328 is configured to grip the rim of an ammunition cartridge such that when the lugs 268 (see FIG. 11) unlock from barrel extension lugs 274 (see FIG. 33) and the bolt assembly 252 moves rearward, the claw portion 328 pulls the ammunition cartridge out of the firing chamber. As shown in FIGS. 14 and 16-17, the claw portion 328 includes a leading edge 340 and a notch 344 disposed in a lower surface 348 of the extractor 320. The leading edge 340 may be rounded or chamfered to encourage the claw portion 328 to slide over an edge of the rim and then seat the rim in the notch 344 during forward movement of the bolt assembly 252. The notch 344 is configured to mate with a complementary curved portion of the rim of the ammunition cartridge. As such, the notch 344 is arcuate or curved in a circumferential direction so as to engage the complementary curved portion of the rim of a cartridge casing.

The biased portion 332 is configured to ensure that the rim of the cartridge casing remains within the notch 344 until the cartridge casing is ejected from the firearm 100 by way of the ejector 300 (see FIG. 12). The biased portion 332 is configured to be biased away from the bolt 256 by way of springs disposed between the biased portion 332 and the bolt 256. In the illustrated embodiment of FIG. 12, the bolt assembly 252 includes a primary spring 288 and a secondary spring 292 that are configured to press the biased portion 332 away from the body of the bolt 256. As shown in FIG. 14, a primary counterbore 352 and a secondary counterbore 356 are concentrically disposed in the lower surface 348 of the biased portion 332. The primary and secondary counterbores 352, 356 are configured to respectively retain the primary and secondary springs 288, 292 disposed between the bolt 256 and the biased portion 332. It is contemplated that the primary and secondary springs 288, 292 provide a cooperative spring force that ensures that the notch 344 reliably engages with the rim of the cartridge casing.

As shown in FIG. 14, the pivot portion 336 is disposed underneath the extractor 320. The pivot portion 336 serves to couple the extractor 320 with the bolt 256 and presses the claw portion 328 into the forward recess 264 (see FIG. 11) due to the forces acting on the biased portion 332 by the springs 288, 292. As shown in FIGS. 14 and 16, the pivot portion 336 comprises parallel prongs 360 that extend from the lower surface 348 of the extractor 320. A transverse hole 364 is disposed in the parallel prongs 360 and is configured to receive an extractor pin, such as the extractor pin 296 disclosed in connection with FIG. 12. As described above, the extractor pin 296 causes the extractor 320 to move in a seesaw manner when the claw portion 328 engages an ammunition cartridge. Thus, the pivot portion 336 and the springs 288, 292 allow the leading edge 340 to move over the rim of the cartridge and then cause the notch 344 to remain fixedly engaged with the rim of the cartridge until the bolt assembly 252 is withdrawn from the breech of the firing chamber, allowing the ejector 300 and to throw the cartridge free of the firearm 100.

It is contemplated that any of various hardened materials may be incorporated into the extractor 320, without limitation. In some embodiments, for example, the extractor 320 may comprise a steel material, such as a hardened stainless steel. The hardened steel material may comprise a steel alloy, such as 4340 steel alloy. In some embodiments, the hardened steel material comprising the extractor 320 may be further treated to provide additional durability. In other embodiments, the extractor 320 may comprise titanium, carbon steel, other steel alloys, and/or other materials that are highly resistant to wear. In some embodiments, at least a portion of the extractor 320 may be heat treated. In some embodiments, at least a portion of the extractor 320 may be polished and/or has a nitride finish to provide desired frictional properties that facilitate sliding of the claw portion 328 over the rim of an ammunition cartridge. It is contemplated that other finishing techniques, surface treatments, and the like may be incorporated into the extractor 320, without limitation, to provide desired surface properties of the extractor 320.

FIGS. 18-20 illustrate an exemplary embodiment of a bolt 380 that may be incorporated into the bolt assembly 252 of FIGS. 11-12, in accordance with the present disclosure. The bolt 380 is substantially identical to the bolt 256 shown in FIG. 11-12. As such, the bolt 380 is a generally cylindrical member having a forward recess 384 surrounded by multiple lugs 388, and a side recess 392. The forward recess 384 is configured to engage with the rim of an ammunition cartridge, while the lugs 388 are configured to engage with barrel extension lugs 274 (see FIG. 33). The lugs 388 and the barrel extension lugs 274 cooperate to keep the ammunition cartridge in battery during firing the ammunition cartridge. The side recess 392 is configured to house an extractor, such as the extractor 320 discussed in connection with FIGS. 13-17.

As shown in FIG. 19, the lugs 388 comprising the bolt 380 having a 70-degree rear angle 396 to reinforce the lugs 388. The rear angle 396 of the lugs 388 produces a 26% increase in bolt 380 size at the same area of the bolt lugs 388. Further, as shown in FIG. 20, the bolt 380 includes an increased bolt diameter 400 while the lugs 388 have an unchanged outer diameter. The increased bolt diameter 400 operates to prevent a thin “web” from becoming a crack initiation point that reduces the life of the bolt 380. Experimental observations have demonstrated that the rear angle 396 of the lugs 388 and the increased bolt diameter 400 greatly increase the life of the bolt 380.

Moreover, in some embodiments, the bolt 380 may be used in cooperation with a reinforced extractor 320 and a fluted firing pin (not shown). The fluted firing pin serves to keep the weight of the firing pin at substantially a mil-spec weight. As will be appreciated, the firing pin adapted for use with the bolt 380 is longer than mil-spec, which added about 1-gram greater mass, and thus fluting the firing pin removes the additional mass. Further, it is contemplated that the fluted firing pin may enable the firing pin to operate when there is fluid in the carrier group.

FIG. 21 illustrates an exemplary embodiment of an extractor pin 420 that may be coupled with an extractor and bolt, such as the extractor 320 and the bolt 380, according to the present disclosure. The extractor pin 420 comprises a generally elongated member having a center portion 428 disposed between end portions 432. The center portion 428 has a larger diameter than the diameter of the end portions 432. A bevel 440 joins the center portion 428 with each of the end portions 432. As described herein, the larger center portion 428 is configured to inhibit pivoting forces from causing the extractor pin 420 to wander out of the holes in the bolt 380 that support the extractor pin 420.

As shown in FIGS. 22-23, the end portions 432 are configured to loosely seat within transverse holes 436 disposed in the bolt 380 while the center portion 428 is configured to loosely seat within the hole 364 (see FIGS. 24-25) of the extractor 320. More specifically, the force on the extractor 320 due to the springs 288, 292 (see FIG. 12) lifts the end portions 432 to the top of the transverse holes 436, thereby producing a gap 444 between the end portions 432 and the bottom of the transverse holes 436. The larger diameter of the center portion 428 maintains the centered position of the extractor pin 420 disposed between the transverse holes 436. Experimental observations have shown that the larger diameter of the center portion 428 and the force on the extractor 320 due to the springs 288, 292 prevent the extractor pin 420 from wandering out of the transverse holes 436, as can happen with standard straight extractor pins.

Turning to FIGS. 24-25, the extractor pin 420 is shown coupled with the extractor 320 described in connection with FIGS. 13-17. As shown in FIG. 24, the center portion 428 is inserted through the hole 364 such that the end portions 432 extend beyond the parallel prongs 360. As best shown in FIG. 25, the bevels 440 align with side edges 348 of the extractor 320 such that that the center portion 428 will remain centered between the transverse holes 436, as described above. Further, the exterior diameter of the center portion 428 shares a loose fit with the inner diameter of the hole 364, allowing the extractor 320 to pivot on the extractor pin 420.

Moreover, as described above, the extractor pin 420 shares a loose fit in the transverse holes 436 of the bolt 380 rather than being press fit into the transverse holes 436. More specifically, the transverse holes 436 can have an inner diameter that is large enough to allow passage of the center portion 428 during removal of the extractor 320 from the bolt 380. As such, a practitioner can remove the extractor 320 from the bolt 380 by simply pressing downward on extractor 320 and using a punch to nudge the extractor pin 420 through the transverse holes 436 and out of the bolt 380.

FIGS. 27-28 illustrate an exemplary embodiment of an upper receiver 104 configured for use in a direct gas impingement operated firearm, such as the firearm 100. The upper receiver 104 is a generally longitudinal member having a barrel tenon portion 452 at a front of the upper receiver 104, a picatinny rail 456 disposed along a top of the upper receiver 104, and an opening 460 at a rear of the upper receiver 104. Picatinny rail 456 facilities a practitioner mounting accessories, such as a scope or a flashlight, while the opening 460 accommodates the reciprocating motion of the bolt carrier group. As will be recognized, the upper receiver 104 defines an internal cavity 464 extending longitudinally in a direction parallel to the length of the firearm 100. The internal cavity 464 is configured to slidably receive the bolt carrier 144 (see FIGS. 2 and 6-7) for axially reciprocating recoil movement therein.

As best shown in FIGS. 29-30, the barrel tenon portion 452 is disposed between a front surface 468 of the upper receiver 104 and a front surface 472 of the barrel tenon portion 452. The barrel tenon portion 452 generally comprises threads 476 that extend circumferentially from the front surface 472 to an unthreaded “boss” 480 disposed adjacent to the front surface 468. The threads 476 are configured to couple the barrel 116 with the upper receiver 104. The unthreaded boss 480 is configured to reinforce the barrel 116 (see FIG. 1) against barrel deflection and adds thermal mass that absorbs heat from the barrel 116 more effectively. Experimental observations have shown that stiffness in the upper receiver 104 directly translates into greater accuracy of the firearm 100. As such, the illustrated embodiment of the barrel tenon portion 452 directly improves firing accuracy of the firearm 100.

As best shown in FIG. 29, the upper receiver 104 includes an ejection channel 484 positioned forward of the ejection port 120. As will be appreciated, the firearm 100 generally operates at a higher rate of speed over time, as the firearm 100 wears due to use. The higher rate of speed of operation can cause ejected shells to move more and more forward. As such, ejected shells can bounce back into ejection port 120 and cause a malfunction. Experimental observations have demonstrated that positioning the ejection channel 484 forward of the ejection port 120 prevents shells from bouncing back into the ejection port 120 and jamming the firearm 100.

With continuing reference to FIG. 29, a forward assist receiver 488 is disposed on the right-hand side of the upper receiver 104 and rearward of the ejection port 120. The illustrated embodiment of the forward assist receiver 488 is positioned closer to the barrel tenon portion 452 than the forward assist receivers of conventional upper receivers. The position of the forward assist receiver 488 is configured to position a forward assist in a more ergonomic location along the length of the firearm 100. Further, the position of the forward assist receiver 488 serves to reduce the number of forward assist notches that must be machined into the bolt carrier (not shown) comprising the firearm 100.

As shown in FIGS. 29-30, the upper receiver 104 comprises a front lower lug 492 and a rear lower lug 496 that are configured to couple the upper receiver 104 with a lower receiver 108 (see FIG. 1) by way of suitable pins. The illustrated embodiment of the rear lower lug 496 is configured to have a lengthened engagement surface with the corresponding mating slot in the lower receiver 108 to reduce roll and lateral play of the upper receiver 104 relative to the lower receiver 108. Specifically, the rear lower lug 496 is increased in length so as to remove a chamfer that is typical of conventional firearms. Further, the rear lower lug 496 is configured to, via tolerancing, minimize side-to-side wobbling of the rear lower lug 496 in a mating pocket of the lower receiver 108. Further, in the illustrated embodiment, the rear lower lug 496 is joined with the upper receiver 104 by way of a first radius portion 500 and a second radius portion 504. The second radius portion 504 is configured to reduce stresses that can break off the rear lower lug 496 from the upper receiver 104. In particular, the second radius portion 504 is configured to prevent the formation of cracks that would otherwise occur and eventually cause the rear lower lug 496 to separate from the upper receiver 104.

Turning, now, to FIG. 30, a cam strike face 508 is disposed on the left-hand side of the upper receiver 104. The cam strike face 508 comprises a window 512 and threaded holes 516 disposed in a thickened portion 520. The window 512 is configured to receive a cam strike face (not shown) that provides a reinforced edge of a cam pocket (not shown) within the internal cavity 464 of the upper receiver 104. As such, the window 512 extends through the sidewall of the upper receiver 104 and is configured to receive the cam strike face in the form of an exterior insert that advantageously reinforces the edge of the cam pocket. The threaded holes 516 are configured to receive fasteners that retain the cam strike face in the window 512. Thus, the threaded holes 516 and the window 512 enable the cam strike face to be installed from the outside of the upper receiver 104.

With continuing reference to FIG. 30, window 512 is surrounded by a counterbored area 524 that has a front end 532 and a rear end 536. The front and rear ends 532, 536 are configured to respectively receive front and rear edges of an exterior portion of the cam strike face such that the cam strike face cannot be improperly installed into the window 512. The threaded holes 516 are positioned with respect to the window 512 such that the exterior portion of the cam strike face is retained in the counterbored area 524 and is flush with the exterior surface of the upper receiver 104 when the fasteners are tightened into the threaded holes 516. In some embodiments, the fasteners may be locked into the threaded holes 516 to provide a permanent assembly of the cam strike face.

As best shown in FIG. 30, the left-hand side of the upper receiver 104 includes a raised portion 540 that partially surrounds an auxiliary bolt catch release area 544. As will be appreciated, the auxiliary bolt catch release area 544 accommodates operation of an auxiliary bolt catch release lever (not shown) enables operation of a bolt catch from the left-hand side of the firearm 100. The raised portion 540 is configured to prevent a practitioner from inadvertently pressing the auxiliary bolt catch release lever, as well as contributing to an aesthetically appealing “finished” appearance to the upper receiver 104.

Turning, again, to all of FIGS. 27-30, the upper receiver 104 comprises a reinforced wall portion 548 adjacent to the barrel tenon portion 452. As will be appreciated, the reinforced wall portion 548 generally comprises an increasing thickness of the sidewalls of the upper receiver 104 leading up to the barrel tenon portion 452. Like the unthreaded boss 480, the reinforced wall portion 548 is configured to reinforce the barrel 116 (see FIG. 1) against barrel deflection and add thermal mass that absorbs heat from the barrel 116 more effectively. As stated hereinabove, experimental observations have shown that stiffness in the upper receiver 104 directly translates into greater accuracy of the firearm 100. As such, the reinforced wall portion 548 directly improves firing accuracy of the firearm 100.

FIGS. 31-32 illustrate an exemplary embodiment of a barrel extension 560 that is configured to avoid misalignment during installation into the upper receiver 104. The barrel extension 560 includes a short ring 564 and a flange 568 that share a cylindrical middle section 572. As best shown in FIG. 33, a “zero-fit” installation of the barrel extension 560 comprises having the short ring 564 centered within the upper receiver 104 while also having a front surface 576 of the flange 568 squarely fitted against the front surface 472 of the upper receiver 104. Zero-fitting the barrel extension 560 is known to improve the accuracy of the firearm 100, however inaccuracy may be introduced into the firearm 100 by attempting to zero-fit an entire length of the barrel extension. In the illustrated embodiment, therefore, the cylindrical middle section 572 has a bit smaller diameter than the short ring 564. The cylindrical middle section 572 is adapted to receive an adhesive after the short ring 564 and the front surface 576 of the flange 568 have been zero-fitted into the upper receiver 104.

As shown in FIG. 32, the barrel extension 560 includes a feed ramp 580 that is optimized to prevent ammunition rounds from nosediving during being moved into battery. In the illustrated embodiment, the feed ramp 580 can have a roughly 42-degree angle. Further, the barrel extension 560 includes multiple lugs 274, a lug locking recess 584 and inner threads 588. As will be appreciated, the lug locking recess 584 provides clearance for bolt lugs 268 (see FIGS. 11-12) to enter the lug locking recess 584 and rotate into contact with lug contact surfaces 592 of the lugs 274. The inner threads 588 facilitate coupling the barrel 116 with the upper receiver 104.

As is known in the art, heat treatment (i.e., carburizing) can significantly change the dimensions of a component. As such, it is contemplated that the barrel extension 560 can be advantageously heat treated before further machining is performed. Once the heat treatment is finished, the lug locking recess 584 can be ground out and the inner threads 588 can be cut, leading to greater perpendicularity of the surfaces comprising the barrel extension 560. In particular, machining the barrel extension 560 after heat treating has been found to cause all the bolt lugs (not shown) to contact the lug contact surfaces 592 when the bolt is locked. Further, heat treating the barrel extension 560 before cutting the inner threads 588 eliminates a need to mask the inner threads 588 during carburization, thus reducing time and cost during heat treatment.

FIG. 33 is a cross-sectional view of an exemplary embodiment of a barrel extension 560 coupled with a barrel tenon portion 452 of an upper receiver 104. The barrel extension 560 is zero-fit into the barrel tenon portion 452 to reduce perpendicularity errors when the barrel 116 is coupled with the upper receiver 104. As described above, a zero-fit installation of the barrel extension 560 comprises having the short ring 564 centered within the upper receiver 104 while also squarely fitting the front surface 576 of the flange 568 against the front surface 472 of the upper receiver 104. In the illustrated embodiment, an adhesive is applied to the cylindrical middle section 572 to avoid introducing inaccuracy into the firearm 100 by attempting to zero-fit the entire length of the barrel extension 560.

FIGS. 34-35 illustrate an exemplary embodiment of a handguard 132 that may be incorporated into the firearm 100 of FIG. 1, according to the present disclosure. The handguard 132 is a generally elongated, hollow cylinder having a distal end 600 and a proximal end 604. An opening 608 extending through the handguard 132 is configured to allow the barrel 116 of the firearm 100 to extend through the handguard 132, as shown in FIG. 1. As best shown in FIG. 35, the opening 608 includes a long recess 612 disposed along an upper side of the handguard 132. The recess 612 is configured to provide clearance for a front sight (not shown) comprising the firearm 100 to be passed through the opening 608 during installing the handguard 132 onto the firearm 100.

As shown in FIGS. 34-35, the handguard 132 has a generally octagonal cross-sectional shape. An upper accessory rail 616 is disposed along a top of the handguard 132 while a lower accessory portion 620 and a series of M-Lok slots 624 are disposed along a bottom of the handguard 132. In the illustrated embodiment, the upper accessory rail 616 comprises a Picatinny rail while the lower accessory portion 620 comprises an ARCA rail. The Picatinny rail may be used to mount any of various lighting and/or sighting accessories to the firearm 100. As will be appreciated, the ARCA rail may be configured to support a camera. Further, in some embodiments, the ARCA rail may be used to support the firearm 100 by way of a bipod or a tripod stand for precision shooting. As such, the ARCA rail includes a longitudinal slot 628 and a transverse slot 632 that are configured to facilitate fastening a camera, a tripod stand, or other desired accessories to the firearm 100. Further, a multiplicity of M-Lok slots 624 may be arranged along the sides of the handguard 132 to facilitate mounting accessories in locations of the handguard 132 other than on the upper accessory rail 616 and the lower accessory portion 620.

As best shown in FIGS. 36-37, a pair of slots 636 is disposed near the proximal end 604 of the handguard 132. The slots 636 are perpendicular to the opening 608 and configured to support a pair of locks 640, as shown in FIG. 37. The locks 640 are configured to fixate an inner contact surface 644 of the handguard 132 with a barrel nut area (not shown) of the barrel 116 such that the handguard 132 may be mounted onto the firearm 100 as shown in FIG. 1.

As best shown in FIG. 36, a drive screw 648 may be threadably engaged with the locks 640 so as to facilitate moving the locks 640 inward and outward simultaneously. As such, tightening the drive screw 648 moves the locks 640 inward and thus pushes the handguard 132 rearward toward a front surface of the upper receiver 104. Thus, the locks 640 give direct alignment of the handguard 132 with the upper receiver 104. Further, clamping the locks 640 onto the barrel nut area transfers any loads on the handguard 132 into the upper receiver 104 directly instead of onto a barrel tenon portion of the firearm 100. As such, the locks 640 improve the strength of the upper receiver 104, reduce bending forces on the upper receiver 104, and reduce the amount of torque required to mount the handguard 132. Further, it is contemplated that the locks 640 may potentially enable suppressor mounting onto the handguard 132.

FIGS. 38-39 illustrate an exemplary embodiment of a lock assembly 652 that may be used to attach to the handguard 132 of FIGS. 34-35 to the firearm 100 of FIG. 1, according to the present disclosure. The lock assembly 652 includes a pair of locks 640 that are threadably engaged with opposite ends of a drive screw 648. The drive screw 648 is threaded symmetrically with left-hand and right-hand threads so that rotating the drive screw 648 moves both locks 640 inward and outward simultaneously, as discussed hereinabove in connection with FIGS. 36-37. As shown in FIG. 38, each lock 640 comprises an adjustable contact surface 656 and a taper surface 660. The adjustable contact surface 656 and the taper surface 660 have diameters configured such that the surfaces 656, 660 mate with corresponding surfaces on the barrel nut area of the firearm 100. Further, the surfaces 656, 660 are configured such that tightening the locks 640 pushes the handguard 132 rearward toward the front surface of the upper receiver 104, as described above.

FIG. 40 illustrates an exemplary embodiment of a drive screw 648 that may be implemented in the lock assembly 652 of FIGS. 38-39, in accordance with the present disclosure. The drive screw 648 shown in FIG. 40 includes a first threaded portion 664 and a second threaded portion 668 disposed on opposite ends of the drive screw 648. The first threaded portion 664 and the second threaded portion 668 share an intervening smooth center portion 672. The first and second threaded portions 664, 668 are configured to engage with threaded holes 680 shown in FIG. 39. The first and second threaded portions 664, 668 are threaded symmetrically with left-hand and right-hand threads so that rotating the drive screw 648 moves the locks 640 inward and outward simultaneously, as discussed hereinabove in connection with FIGS. 36-37. The smooth center portion 672 allows the drive screw 648 to rotate with respect to the handguard 132. A shaped opening 676 disposed in each of the ends of the drive screw 648 is configured to enable rotation of the drive screw 648 with respect to the locks 640 by way of a suitable tool.

FIGS. 41-42 illustrate an exemplary embodiment of an ambidextrous bolt catch release assembly 684, according to the present disclosure. The ambidextrous bolt catch release assembly 684 comprises a bolt catch release paddle 688 that is configured to be operated from either side of the lower receiver 108. As shown in FIGS. 41-42, the bolt catch release paddle 688 is disposed at the front of a trigger guard 692 to provide easy access from either side of the lower receiver 108. A bolt catch shaft 696 and spring 700 extend vertically through the lower receiver 108, from the bolt catch release paddle 688 to a bolt catch 704. A vertical hole 706 in the lower receiver 108 is configured to slidably house the bolt catch shaft 696 and the spring 700. As best shown in FIG. 43, the bolt catch shaft 696 passes through an elongate hole 710 in the middle of a magazine catch release button 708. As will be recognized, the magazine catch release button 708 can be operated from either side of the lower receiver 108 to actuate a magazine catch 712. The elongate hole 710 allows the magazine catch 712 to be moved left and right with respect to the lower receiver 108 despite the presence of the bolt catch shaft 696.

As shown in FIGS. 41-43, an auxiliary bolt catch release paddle 716 is disposed on the left-hand side of the lower receiver 108 and mechanically engaged with the bolt catch 704. The auxiliary bolt catch release paddle 716 enables operation of the bolt catch 180 from the left side of the firearm 100. It is contemplated that the auxiliary bolt catch release paddle 716 may best serve practitioners that are familiar with conventional firearms that lack the bolt catch release paddle 688 disclosed herein.

Turning, now, to FIGS. 44-45, an exemplary embodiment of the ambidextrous bolt catch release assembly 684 is shown in absence of the lower receiver 108, according to the present disclosure. The ambidextrous bolt catch release assembly 684 includes a bolt catch release paddle 688 and a bolt catch 704 that are disposed at opposite ends of a vertical shaft 696. As shown in FIG. 45, the shaft 696 includes a threaded end 720 that is configured to be threadably engaged with a hole 724 in the bottom of the bolt catch 704, as shown in FIG. 43. In another embodiment, the shaft 696 is joined with the bolt catch 704 by way of a head on an upper end of the shaft 696 that engages with a T-slot cut in the bottom of the bolt catch 704. A lower end 726 of the shaft 696 is configured to be engaged with a hole 730 in the bolt catch release paddle 688. A spring 700 is configured to ride on the shaft 696 and biases the bolt catch 704 is a lowered position in the lower receiver 108.

As will be recognized, the lower position of the bolt catch 704 allows the bolt carrier group to reciprocate freely within the lower receiver 108. Once all ammunition cartridges in the magazine 112 (see FIG. 1) have been spent, the bolt catch 704 is raised by a magazine cartridge follower such that the bolt carrier group is held in a rearward position within the receiver extension 124, allowing the empty magazine 112 to be replaced with another magazine 112 that has fresh ammunition. The bolt catch release paddle 688 or the auxiliary bolt catch release paddle 716 may be used to lower the bolt catch 704 and allow the bolt carrier group to move forward, stripping a fresh ammunition cartridge from the magazine 112 into battery.

The auxiliary bolt catch release paddle 716 comprises a generally T-shaped member that can be pivotally mounted to the lower receiver 108 by way of a pin pivot 728. The auxiliary bolt catch release paddle 716 includes a protrusion 732 that fits into a recess 736 comprising the bolt catch 704. Thus, when the auxiliary bolt catch release paddle 716 moves in a rotational direction 740, due to the pin pivot 728, the protrusion 732 pushes the bolt catch 704 along a downward direction 744 with respect to the lower receiver 108. As such, when the bolt catch 704 has the bolt carrier group locked in a rearward position within the receiver extension 124, the bolt carrier group can be released by pulling downward on the bolt catch release paddle 688 or by pressing the auxiliary bolt catch release paddle 716. The bolt catch 704 may also be engaged to retain the bolt carrier 144 in the rearward position by pushing up on the bolt catch release paddle 688 after manually retracting the bolt carrier group via a charging handle. Further, as shown in FIG. 45, the bolt catch release paddle 688 and the auxiliary bolt catch release paddle 716 include knurls 748 that facilitate a practitioner achieving a firm grip.

Turning, now, to FIG. 46, an exemplary embodiment of a tensioning screw 152 is shown coupled between the upper receiver 104 and the lower receiver 108 of the firearm 100. In general, the tensioning screw 752 is configured to be engaged with a threaded hole 756 in the lower receiver 108 and put into contact with a rear lower lug 496 of the upper receiver 104. The tensioning screw 752 is configured to eliminate receiver wobble and play by protruding up and putting pressure on the lower lug 496 of the upper receiver 104. The tensioning screw 752 can be accessed and adjusted from below by first removing a grip 780, or the tensioning screw 752 can be accessed and adjusted from above by opening the upper and lower receivers 104, 108, as described herein.

FIGS. 47-48 illustrate isometric views of an exemplary embodiment of the tensioning screw 752 for reducing wobble between the upper and lower receivers 104, 108 of the firearm 100, according to the present disclosure. The tensioning screw 752 includes a threaded portion 784 and a head portion 788 with an upper shaped opening 792. The head portion 788 is configured to match the size of the rear lower lug 496 (see FIG. 46) of the upper receiver 104. Experimental observation has demonstrated that the larger head portion 788 more effectively retains its adjustment, as well as more effectively eliminating play between the upper and lower receivers 104, 108.

The upper shaped opening 792 is configured to receive a suitable tool, whereby the tensioning screw 752 can be turned. As shown in FIG. 47, the upper shaped opening 792 can be a Torx receptacle or other suitable type of receptacle. Further, as shown in FIG. 48, a lower shaped opening 796 is disposed in the bottom end of the tensioning screw 752 and is configured to receive a suitable tool for turning the tensioning screw 752. Like the upper shaped opening 792, the lower shaped opening 796 can be a Torx receptacle or other suitable type of receptacle. The upper and lower shaped openings 792, 796 enable adjusting the tensioning screw 752 from the top and bottom of the screw 752. For example, as shown in FIG. 49, the upper shaped opening 792 of the tensioning screw 752 can be accessed by separating the upper and lower receivers 104, 108. As shown in FIG. 50, the lower shaped opening 796 can be accessed by removing the grip 780 (see FIG. 46).

With the head portion 788 exposed, as shown in FIG. 49, the tensioning screw 752 can be adjusted by inserting a suitable tool in the upper shaped opening 792 and turning the screw to change its position in the lower receiver 108. Further, as shown in FIG. 50, the tensioning screw 752 can be adjusted by inserting a suitable tool in the lower shaped opening 796 and turning the screw to change its position in the lower receiver 108. It is contemplated that adjusting the tensioning screw 752 by way of the lower shaped opening 796 offers a practitioner the advantage of directly feeling the degree of tension between the upper and lower receivers 104, 108 as the screw 752 is turned. Alternatively, adjusting the tensioning screw 752 by way of the upper shaped opening 792 enables the practitioner to adjust the tension between the upper and lower receivers 104, 108 without having to first remove the grip 780 from the firearm 100.

While the optimized direct gas operated firearm and methods have been described in terms of particular variations and illustrative figures, those of ordinary skill in the art will recognize that the optimized direct gas operated firearm is not limited to the variations or figures described. In addition, where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the firearm. Additionally, certain of the steps may be performed concurrently in a parallel process, when possible, as well as performed sequentially as described above. To the extent there are variations of the firearm, which are within the spirit of the disclosure or equivalent to the firearm found in the claims, it is the intent that this patent will cover those variations as well. Therefore, the present disclosure is to be understood as not limited by the specific embodiments described herein, but only by scope of the appended claims.