Rifle Upper Receiver Components

Description

PRIORITY CLAIM AND CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. § 119(e)(1) of U.S. Provisional Application No. 63/718,998, filed Nov. 11, 2024, which is hereby incorporated by reference in its entirety.

BACKGROUND

There are tens of millions of AR styled rifles (including AR-15, M16, M4, etc.) in America today. With the western-trained allies also using AR styled rifles, the AR styled rifle is one of, if not the most prolific rifle in the world. The manufacture and sales of AR styled rifles represents a 10 billion dollar per year industry, with most firearms manufacturers around the world producing and/or marketing a version of an AR styled rifle.

AR styled rifles are produced to use various sizes of cartridges, including. 223/5.56 mm NATO, .22-LR, 9×19 mm Parabellum, various shotgun calibers, as well as others, including 7.62×39 mm rounds. The 7.62×39 mm cartridge is a rimless cartridge that was designed by the Soviet Union during World War II for the SKS and AK-47 rifles and others, and has since proliferated throughout the world, being widely used by civilians and militaries nearly everywhere. The use and production of the 7.62×39 mm cartridge in many developing nations means that the manufacturing quality for cartridges produced in the regions can vary by a significant margin. Variations can include the forces produced by the ignited cartridge, including the amount and pressure of the resulting gases.

Using an AR styled rifle reduces or eliminates weapons training for persons familiar with the AR styled rifle (such as Western-trained military personnel, for example). As military and specialized operations can take place anywhere in the world, there is a need for an AR styled rifle that is capable of reliably using the 7.62×39 mm cartridge, without regard for the country of origin and the associated variations in manufacturing quality. Using the 7.62×39 mm cartridge ensures access to ammunition in nearly all parts of the world.

However, without some mitigation, use of the variations of the 7.62×39 mm cartridge can potentially result in lower than expected volume and pressure of gases produced (e.g., 20,000 psi less) which can result in unreliable cycling of the firearm, or higher than normal volume and pressure of gases in some cases (e.g., over 30,000 psi increase) which can be potentially destructive to the AR style rifle and hazardous or deadly to the operator.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is set forth with reference to the accompanying figures. The use of the same reference numbers in different figures indicates similar or identical items.

For this discussion, the devices and systems illustrated in the figures are shown as having a multiplicity of components. Various implementations of devices and/or systems, as described herein, may include fewer components and remain within the scope of the disclosure. Alternately, other implementations of devices and/or systems may include additional components, or various combinations of the described components, and remain within the scope of the disclosure. Shapes and/or dimensions shown in the illustrations of the figures are for example, and other shapes and or dimensions may be used and remain within the scope of the disclosure, unless specified otherwise.

FIG. 1 shows an example AR styled rifle, which is an environment wherein the disclosed embodiments may be practiced.

FIGS. 2A and 2B show right-front perspective views of an example AR style upper receiver, with and without a bolt carrier, respectively, according to an embodiment.

FIGS. 3A and 3B show left-rear perspective views of an example AR style upper receiver, with and without a bolt carrier, respectively, according to an embodiment.

FIG. 4A shows a top view of an example AR style upper receiver, according to an embodiment.

FIGS. 4B and 4C show bottom views of an example AR style upper receiver, with and without a bolt carrier, respectively, according to an embodiment.

FIG. 5A shows a left side view of an example AR style upper receiver, according to an embodiment.

FIG. 5B shows an inside view of the left side of an example AR style upper receiver, according to an embodiment.

FIG. 6A shows a right side view of an example AR style upper receiver, according to an embodiment.

FIG. 6B shows an inside view of the right side of an example AR style upper receiver, according to an embodiment.

FIGS. 7A and 7B show front and back views of an example AR style upper receiver, respectively, according to an embodiment.

FIGS. 8A and 8B show right-front perspective views of an example AR style bolt carrier, showing top and bottom respectively, according to an embodiment.

FIGS. 8C and 8D show left-rear perspective views of an example AR style bolt carrier, showing top and bottom respectively, according to an embodiment.

FIGS. 9A and 9B show right and left side views of an example AR style bolt carrier, respectively, according to an embodiment.

FIG. 9C shows a front view of an example AR style bolt carrier, according to an embodiment.

FIGS. 10A and 10B show top and bottom views of an example AR style bolt carrier, respectively, according to an embodiment.

FIG. 10C shows a back view of an example AR style bolt carrier, according to an embodiment.

DETAILED DESCRIPTION

Overview

Representative implementations of devices and techniques provide novel AR style rifle upper receiver components, including a novel upper receiver and a novel bolt carrier. The novel upper receiver components are an exact fit for an AR style rifle (i.e., the novel upper receiver and novel bolt carrier can be seamlessly interchanged with the upper receiver or bolt carrier of any AR style rifle), and allow the reliable worldwide use of the 7.62×39 mm cartridge.

The novel upper receiver components are visually and tactilely differentiable from standard or prior art AR style upper receiver components, making them identifiable. However, the novel upper receiver components are operated in the same manner as the standard AR style upper receiver components (to avoid the need for specialized training). The novel upper receiver components assemble and disassemble in the same way as standard AR style upper receiver components. However, the shape, features, and performance of the novel components (the upper receiver 110 and the bolt carrier 120) distinguishes the novel components from standard or prior art components. In some cases, a novel upper receiver will accept a standard AR style bolt carrier (with some modifications), and a novel bolt carrier will fit within a standard AR style upper receiver.

Once the novel upper receiver components are installed together, the novel upper receiver 110 is a direct fit on a standard AR style rifle. The novel upper receiver components are designed for added strength and durability to withstand higher than normal volume and pressure of gases. Thus, they are capable of using a variety of 7.62×39 mm cartridges from around the world. The novel upper receiver components are also capable of functioning under water (or after being submerged) and are maintainable using normal AR armoring techniques.

FIG. 1 illustrates an example prior art AR style rifle, which is an environment wherein the disclosed techniques and devices may be employed. Various differences between the novel components disclosed herein are discussed in this document, and the person having skill in the art may note additional differences not specifically discussed herein. The prior art AR style rifle becomes a novel AR style rifle 100 when either or both of the novel upper receiver 110 or the novel bolt carrier 120 are installed thereon/therein.

Referring to FIGS. 1-10C, the following part number designations are used throughout:

Part number	Description
1	Upper Receiver
110	Novel Upper Receiver
102	Novel Upper Receiver Assembly
2	Lower Receiver
3	Buttstock
4	Grip
5	Trigger guard and trigger
6	Magazine well
7	Magazine
8	Handguard
9	Barrel
10	Flash Suppressor
11	Front Sight
12	Barrel Nut
13	Accessory Rail
14	Rear Sight
15	Gas Block (inside Handguard)
16	Gas Tube (inside Handguard)
20	Charging Handle
21	Forward Assist
21b	Forward Assist interior opening
22	Bolt Carrier
120	Novel Bolt Carrier
23	Ejection Port Cover
24	Ejection Port
25	Barrel Attachment with Index
26	Rear Takedown Pin Opening
27	Front Pivot Pin Opening
28	Firing Pin
29	Magazine Well Access
30	Trigger Group Opening
31	Gas Tube Access
32	Bolt
33	Bolt Lug
34	Ejector
35	Guide Rivets
36	Rail Rivets
37	Front Pivot Pin Bushing
38	Rail Recess
39	Rail
40	Upper Guide
41	Charging Handle Groove
42	Extractor
43	Firing Pin Opening
44	Bolt Guide Lug
46	Gas Tube Key
47	Bolt Carrier Boss
48	Cam Opening
49	Cam Pin
50	Firing Pin Keeper
51	Rail Groove
52	Forward Assist Detents
53	Cartridge Guide Rail
54	Gas Vents
55	Guide Rail Leading Surface
56	Carrier Grooves
61	Gas Seal Rings
62	Cam Pin Opening
63	Bolt Stabilizer
64	Firing Pin Entry
65	Bolt Stabilizer Opening
66	Firing Pin Tip
67	Firing Pin Upper Shaft
68	Firing Pin Stop
69	Firing Pin Heel
70	Bearing
71	Firing Pin Lower Shaft
72	Firing Pin Toe
73	Bearing Groove
74	Cam Pin Head
75	Cam Pin Shaft
76	Firing Pin Alignment Hole

Note that in some cases, the use of a part number in the discussion (including the drawings) may refer to the part without necessarily indicating whether the part is a novel part or a prior art part. The discussion will provide details regarding novel aspects of the novel parts indicated.

Referring to FIG. 1, rather than having a single-application receiver as found on some rifles, the AR styled rifles include a modularly designed receiver with separate upper 1 and lower 2 receivers. The lower receiver 2 includes a trigger guard and houses the trigger group 5. The lower receiver 2 also includes a means (e.g., screw-type fitting) for coupling the buttstock 3 and a pistol grip 4. The lower receiver 2 also includes a magazine well 6 for coupling and interchanging various cartridge magazines 7.

Referring also to FIGS. 2A and 2B, an upper receiver 110 includes a coupler 25 for coupling the barrel 9, and the handguard 8. The upper receiver 110 is releasably coupled to the lower receiver 2 using front and rear pins. With the rear takedown pin removed, the upper receiver 110 can be pivoted at the front pin location 27, via the bushing 37, or it can be removed by removing the front pin. The upper receiver 110 also houses the bolt carrier (22 or 120) with the bolt 32 and the firing pin 28. An ejection port 24 is located at the upper receiver 110 for expelling spent casings.

Example Embodiments

Embodiments of modular rifles 100 are disclosed herein, as embodiments with various novel enhancements. Devices, systems, and techniques are also disclosed herein for enhancing modular rifles. Accordingly, the devices, systems, and techniques may be integral to a disclosed rifle 100, or they may be retrofit to a pre-existing rifle (individually or in various combinations).

For example, this document discloses novel upper receiver components, including a novel upper receiver 110 and a novel bolt carrier 120. The novel upper receiver 110 is visually and tactilely differentiable from a common AR style upper receiver 1 and the novel bolt carrier 120 is visually and tactilely differentiable from a common AR style bolt carrier 22, but both are operated without the need for specialized training. The novel upper receiver 110 is assembled to and disassembled from a rifle 100 in a similar way to a standard AR style upper receiver 1. The novel bolt carrier 120 is assembled to and disassembled from (e.g., slidably coupled to) an upper receiver (110 or 1) in a similar way to a standard AR style bolt carrier 22. However, the shape, size and operation of the novel upper receiver 110 and novel bolt carrier 120 are distinguishable from standard AR components.

The novel upper receiver 110 and the novel bolt carrier 120 are both a direct fit on a standard AR style rifle. The novel upper receiver 110 and the novel bolt carrier 120 are designed for added strength, reliability, safety, and durability.

Referring to FIGS. 2A-7B, an example novel AR style upper receiver 110 is shown according to various embodiments. FIGS. 2A, 3A, and 4B show various views of a novel upper receiver 110 with a bolt carrier (22 or 120) disposed within. FIGS. 2B, 3B, 4C, and 5A-7B show a novel upper receiver 110 in similar views, but without a bolt carrier (22 or 120) disposed within, to reveal more of the inside of the upper receiver 110. FIG. 4A shows a top view of a novel upper receiver 110, with or without a bolt carrier (22 or 120). A novel upper receiver 110 with a novel bolt carrier 120 comprises a novel upper receiver assembly 102.

The upper receiver 110 comprises a housing for upper receiver components for a standard or modified AR style rifle. The novel upper receiver 110 is configured to be a direct-fit replacement for a prior art upper receiver 1 on a standard or modified AR style (e.g., modular) rifle. The novel upper receiver 110 can be used with a prior art bolt carrier 22 (with some modification in some cases) or the novel bolt carrier 120 disclosed herein.

The upper receiver 110 is constructed to enclose and contain the bolt carrier (22 or 120) and related components, and to allow their smooth and reliable movement within the upper receiver 110 during firing cycles. The bolt carrier (22 or 120) is arranged to move backward and forward (coaxially with the upper receiver 110 and the barrel 9 of the firearm) within the upper receiver 110 during the firing cycles. Repeated use (e.g., multiple cycles) can cause wear within a prior art upper receiver 1, particularly at locations within the upper receiver where the bolt carrier 22 contacts interior surfaces of the upper receiver 1 during movement, and which can result in less precise movement of the bolt carrier 22 over multiple cycles. The less precise movement of the bolt carrier 22 includes pitch, roll, and/or yaw components added to the bolt carrier's movement during a cycle, which can exacerbate the wear of the upper receiver 1, shortening the useful lifespan of the upper receiver 1. Excessive combustion forces from sub-standard ammunition can further increase the wear and result in the premature destruction of the upper receiver 1.

The novel upper receiver 110 includes multiple features to reduce wear during normal use and to prevent excessive or premature wear caused by excessive combustion forces. These features promote the precise axial movement of the bolt carrier 22 or 120 and reduce or eliminate the less-precise movements discussed above. For example, the novel upper receiver 110 includes added bearing surfaces at various locations affixed within the upper receiver 110 where cycling components are intended to move relative to the upper receiver 110. In other words, the upper receiver 110 is improved at least at multiple areas where the bolt carrier (22 or 120) slides against interior surfaces of the upper receiver 110. Those areas include hardened, reinforced, supplemented, augmented, or otherwise strengthened bearing surfaces (39 and 40).

Additional hardened surfaces may also be used at other locations within the upper receiver 110, where other components move against the interior surfaces of the upper receiver 110. Also, in some cases, the upper receiver 110 includes a front pivot bushing 37. As shown at FIGS. 2A, 3B, and 5A-6B, the front pivot point 27 of the upper receiver 110 can include a front pivot bushing 37 made from a hardened metal such as steel or other alloys. The front pivot bushing 37 provides improved wear characteristics, preventing the front pivot pin opening 27 from enlarging or deforming, and thus greater useful service life of the upper receiver 110. The front pivot bushing 37 is installed within the front pivot pin opening 27 by pressing the bushing 37 or other means to maintain the bushing 37 within the front pivot point 27.

Like a standard or prior art upper receiver 1, the novel upper receiver 110 can be designed so that it can be easily destroyed when necessary, such as to avoid its being used by hostile forces. Accordingly, the novel upper receiver 110 can be primarily manufactured from plastics, polymers, carbon fiber, fiberglass, composites, uncoated aluminum, or other materials that are consumed or rendered permanently unusable with fire.

However, to allow for reliable and prolonged use, the novel upper receiver 110 includes a plurality of hardened metal bearing surfaces (39 and 40) at various locations within the upper receiver 110. Referring to FIGS. 2A-7B, such hardened metal bearing surfaces include guides 40 and rails 39, as shown at the cutaway drawings of FIGS. 5B and 6B. In various embodiments, there can be multiple guides 40 and multiple rails 39. Each of the guides 40 and rails 39 are configured to provide a hardened surface for a bolt carrier (22 or 120) to slide against while moving within the upper receiver 110. In various embodiments, the guides 40 and rails 39 are comprised of hardened steel and like alloys, which may include chromium, molybdenum, nickel, carbon, or other materials to achieve a desired hardness and wear characteristic. Processes such as heat treatment, tempering, quenching, annealing, and others are also contemplated for desired results.

The guides 40 and/or the rails 39 can also provide one or more hardened structures for features of the bolt carrier (22 or 120) to engage, so as to provide more precise coaxial movement of the bolt carrier (22 or 120) within the upper receiver 110. Features such as grooves, recesses, protrusions, tabs, and like features of the bolt carrier (22 or 120) can “ride on” or be guided by the one or more guides 40 and/or rails 39 to provide precise axial movement of the bolt carrier (22 or 120). In one example, a groove 51 of a bolt carrier 120 engages a rail 39 within the upper receiver 110 to guide the precise axial movement of the bolt carrier (22 or 120). In other examples, upper bearing surfaces 47 of the bolt carrier 120 can move against the bearing surfaces of guides 40 within the upper receiver 110. Guides 40 and rails 39 provide improved precision of movement of the bolt carrier (22 or 120) with improved wear characteristics for the upper receiver 110 and for the bolt carrier 120.

As shown at FIG. 4C, the guides 40 comprise a pair of hardened metal strips that can be positioned in a horizontal orientation on either side of the charging handle groove 41, so as to contact an upper portion of the bolt carrier (22 or 120) such as the body of the bolt carrier (22 or 120) or the upper bolt carrier bosses 47 along the length of the bolt carrier (22 or 120). The guides 40 can be substantially rectangular or trapezoidal (or any other shape that extends most of the length of the upper receiver 110 and has a straight, flat, or level lower edge) and extend most of the length of the upper receiver 110. The guides 40 can be disposed within the upper receiver 110, so that a planar side of a guide 40 is parallel to the side wall of the upper receiver 110, and an edge of the guide 40 (e.g., lower edge) is arranged to be in contact with the bolt carrier (22 or 120). For example, two guides 40 can be disposed on either side of the charging handle groove 41, with lower edges of the guides 40 being arranged to contact the bolt carrier (22 or 120).

Referring to FIGS. 2A-3B and 5A-6A, rivets, screws, or like fasteners 35 can be used to fix the guides 40 to the inside surface of the upper receiver 110. The rivets, screws, or like fasteners 35 are shown on the left side and the right side of the upper receiver 110 in the drawings, indicating an example of the arrangement of the guides 40 within the upper receiver 110. In some cases, guides and associated fasteners may be disposed on only one side of the upper receiver 110. Alternatively, other fasteners or techniques may be used to fix the guides 40 to the inside surface of the upper receiver 110, such as adhesives, friction, welds, and so forth. In some cases, the guides 40 may be formed within the upper receiver 110 during manufacturing. For example, the guides 40 may be printed using 3D printing techniques and materials, molded, or otherwise formed within the upper receiver 110.

In various examples, guides 40 and/or rails 39 are fixed to the inside surface of the novel upper receiver 110 using rivets, screws, or like fasteners 35 & 36, as shown at FIGS. 2A-3B and 5A-6A. In some cases, fasteners 35 and/or 36 may extend through the sidewall of the upper receiver 110. Example guides 40 are shown at FIG. 4C from the bottom of the upper receiver 110, and at FIGS. 5B and 6B from the inside views of the upper receiver 110. The guides 40 are fastened or formed securely to the upper portion of the inside surface of the upper receiver 110 so as not to shift during use.

An example rail 39 is also shown at FIGS. 4C and 5B, fastened to an inside surface of the upper receiver 110 in a horizontal orientation. Rivets, screws, or like fasteners 36 are shown fixing the rail 39 to the inside of the left side of the upper receiver 110. The novel upper receiver 110 can include a horizontally oriented recess 38 in the inner sidewall, along a length of the sidewall. The recess 38 can be generally rectangular shaped to accommodate the shape and size of the rail 39. For instance, the recess 38 is shaped and sized so that the rail 39 fits snugly within the recess 38.

In alternate embodiments, other fasteners or techniques may be used to fix the rail 39 to the inside surface of the upper receiver 110 or within the recess 38, such as adhesives, friction, welds, and so forth. In some cases, the rail 39 may be formed within the upper receiver 110 during manufacturing. For example, the rail 39 may be printed using 3D printing techniques and materials, molded, or otherwise formed within the upper receiver 110.

The recess 38 at the inside surface results in a horizontally oriented protrusion 38a of the sidewall on the outside surface of the upper receiver 110. Thus, the protrusion 38a on the outer surface can be rectangular shaped as well, reflecting the shape of the recess 38 of the inner surface. The rail 39 is set into the recess 38 and protrudes from the recess 38 to engage the bolt carrier 120 as the bolt carrier 120 moves within the interior of the upper receiver 110. For example, the recess 38 is formed with a depth that is substantially less than the thickness of the rail 39.

The rail 39 provides a hardened surface for the bolt carrier 120 to move against or on, and guides the bolt carrier 120 as the bolt carrier 120 moves within the interior of the upper receiver 110, to promote precise movement of the bolt carrier 120. As mentioned, the rail 39 engages a groove 51 disposed into the side of the bolt carrier 120, so that the bolt carrier 120 “rides on” the rail 39. This riding action minimizes or eliminates any pitch, roll, or yaw components of the coaxial movement of the bolt carrier 120.

FIGS. 8A-10C show various views of a novel bolt carrier 120 which can be used with a prior art upper receiver 1 or with the novel upper receiver 110. When the novel bolt carrier 120 is combined with the novel upper receiver 110, a novel upper receiver assembly 102 is the result. FIGS. 2A, 3A, and 4B show a novel upper receiver assembly 102 when the novel bolt carrier 120 is included.

A bolt carrier (22 or 120) is constructed to hold a bolt and firing pin and related components. The bolt carrier (22 or 120) carries the bolt and firing pin as the bolt carrier (22 or 120) moves during a firing cycle. The bolt loads a cartridge and holds the cartridge stable for firing at one end of travel of the bolt carrier (22 or 120), with the firing pin activating combustion, and then the bolt clears the spent casing while moving to the other end of the travel of the bolt carrier (22 or 120) during a cycle.

Referring to FIGS. 8A-10C, the novel bolt carrier 120 includes a plurality of improvements over a prior art bolt carrier 22. For example, the novel bolt carrier 120 is constructed to include thicker walls for greater strength. Referring to FIG. 8C, the dimension “D” refers to the thickness of the walls of the bolt carrier 120. The thickness “D” can be at least 50% greater than the like dimension of a prior art bolt carrier 22. In alternate embodiments, the thickness “D” may be lesser or greater than 50%.

The bolt carrier 120 has at least one groove 51 running along a length of a side of the bolt carrier 120 that interfaces with the hardened metal rail 39 fastened to the inside wall of the novel upper receiver 110. The groove 51 may comprise a rectangular channel as shown, or a channel having another profile configured to interface with the rail 39. The rail groove 51 of the novel bolt carrier 120 rides on the rail 39, and the bolt carrier 120 is held in correct alignment by the rail 39. The bolt carrier 120 moves true on the rail 39 during cycling without pitch, roll, or yaw components. The rail 39 and groove 51 combination can be similar in construction and operation to the rail 134 and groove 132 combination described in U.S. Pat. No. 10,101,109 to Caudle, issued Oct. 16, 2018, and incorporated herein in its entirety.

The bolt carrier 120 also includes bearing-type bosses 47 on its upper and lower surfaces as shown in the figures. The bosses 47 run partially or fully the length of the bolt carrier 120, in a direction corresponding to the length of the bolt carrier 120. The bosses 47 contact the inner guides 40 of the upper receiver 110, during bolt carrier 120 movement within the upper receiver 110 during cycling. The guides 40 within the upper receiver 110 may also be hardened metal pieces (steel, titanium, or other hardened metals) that are fastened into the upper receiver 110 using rivets, screws, or like fasteners 35.

As shown at FIGS. 8B and 8D, the novel bolt carrier 120 has a stepped cartridge guide rail 53 that is different in profile shape and has a lower surface that is flatter and wider than the prior art. The step-like cartridge guide rail 53 comprises a set of low and flat steps disposed on the underside of the bolt carrier 120, near the front of the bolt carrier 120. The guide rail 53 pushes the cartridges in the magazine down against the magazine spring, to give sufficient room for bolt carrier 120 cycling during a backward movement of the bolt carrier 120. The step-like shape of the novel guide rail 53 pushes the top cartridge further down into the magazine than with a prior art bolt carrier 22, providing smoother cycling. Additionally, the flatter and wider surface of the novel guide rail 53 contacts the upper cartridge more squarely than a prior art bolt carrier 22, which tends to push the cartridge at an angle due to its narrow pushing surface. The result is little to no rotational torque on the bolt carrier 120 from the pushing force, during cycling, in contrast to the prior art.

As shown at FIGS. 8B and 8D, the novel bolt carrier 120 may also include an angled guide rail leading surface 55. The novel guide rail leading surface 55 is much more prominent (e.g. wider and longer), and has a much shallower angle than on a prior art bolt carrier 22. The profile of the novel guide rail leading surface 55 matches the profile, including the width, of the bolt guide lug of the bolt, for smoother and more reliable feeding of a cartridge into the firing chamber during cycling.

Referring to FIGS. 8C, 8D, 9C, and 10C, the novel bolt carrier 120 includes a cylindrical bearing surface 802 at the rear of the bolt/firing pin enclosure. The bearing surface 802 is a polished interior bearing surface, having an interior cylindrical shape, configured to interface with a novel bolt, which includes a rear stabilizer. The rear stabilizer is a tube-like structure appended to the rear section of the novel bolt, that extends beyond the end of a prior art bolt and includes a bearing surface on an outer surface of the stabilizer. The outer tube-like bearing surface of the stabilizer closely fits within the inner cylindrical bearing surface 802 of the bolt carrier 120, for precise movement of the bolt within the bolt carrier 120, without wobble. For instance, the tolerance between the stabilizer of the bolt and the bearing surface 802 of the bolt carrier 120 is a bearing-on-bearing tolerance (0-5 hundredths of an inch, for example).

On a prior art bolt carrier, the opening at the rear of the bolt/firing pin enclosure is larger, since there is no stabilizer on the end of a prior art bolt, and there is no bearing surface. The larger opening in combination with a narrow rear section of the bolt can contribute to wobble of the bolt when moving within the bolt carrier. Additionally, the material of the bolt carrier is thinner at this point (particularly at the lower portion of the opening), resulting in a potential weak point in the bolt carrier.

As shown at FIGS. 8B, 8D, and 10B, the novel bolt carrier 120 may also include gas vents 54 on its underside. The gas vents 54 reduce a pressure differential that can occur at the rear of the bolt during combustion, reducing or eliminating carbon build-up on the bolt. The gas vents 54 allow high pressure combustion gases to escape from the inside of the bolt carrier 120, and to vent out through the upper receiver 110. The gas vents 54 may be disposed near or within the grooves 56 on the underside of the bolt carrier 120, near the front of the bolt carrier 120. This positions the gas vents 54 near the back of the firing pin. Less carbon build-up on the firing pin results in better movement of the firing pin during cycling.

Although various implementations and examples are discussed herein, further implementations and examples may be possible by combining the features and elements of individual implementations and examples.

CONCLUSION

Although the implementations of the disclosure have been described in language specific to structural features and/or methodological acts, it is to be understood that the implementations are not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as representative forms of implementing the claims.