HYBRID PROJECTILE

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates generally to ammunition for firearms, and more specifically, to hybrid projectiles for firearm ammunition and methods for making the same.

Description of Related Art

Ammunition cartridges of the type commonly used in modern firearms are generally well known in the art. These ammunition cartridges typically include a cylindrical case that carries an internal payload, e.g., propellant powder, and has an open end for receiving a projectile. The size and shape of the cartridge and projectile will typically be dependent on the firearm used. The end opposite the projectile receiving end is typically closed about a means for igniting the internal payload, e.g., a primer is usually disposed in the base end of a cartridge. When chambered in a firearm, the projectile faces the bore of the firearm and the base end faces a firing mechanism, e.g., firing pin. When the primer is struck by the firing pin, a flash is produced which ignites the propellant powder within the case to propel the projectile down the bore and out of the muzzle of the firearm.

Coating or jacketing projectiles such as lead bullets for firearms is well known in the art of making ammunition. Full metal jacketing (FMJ) stabilizes the shape of lead bullets and reduces misfeeding when chambering rounds. FMJ also allows for higher muzzle velocities and reduces the metal deposition in the bore of the firearm. Total metal jacketing (TMJ) consists of electroplating a thin layer of metal, usually copper, over the entire surface of a bullet made from softer metal such as lead. Generally, TMJ improves projectile accuracy and prevents the release of molten lead from the muzzle of the firearm.

Processes such as FMJ and TMJ can undesirably add weight to the projectile, which limits velocity of the projectile and also reduces accuracy at long range. Further, FMJ and TMJ projectiles will transfer heat to the bore of the firearm barrel as the projectile is passed therethrough. The heat transfer caused by the projectile can reduce the effective life of a given firearm barrel.

What is needed is a method for coating a projectile that achieves the advantages of FMJ and TMJ without adding excessive weight that adversely affects projectile ballistics.

SUMMARY OF THE INVENTION

Hybrid projectiles according to the present invention overcome the above mentioned problems and possess improved ballistic characteristics. The hybrid projectiles disclosed herein are lighter than a conventional metal bullet of the same caliber and therefore can achieve higher velocities utilizing the same payload. Further, the polymer material forming the jacket reduces heat transferred to the firearm barrel and can therefore prolong the useful life of a given firearm.

In one embodiment, the hybrid projectile includes a metallic core having an ogive that tapers into the nose. The rearward end of the core defines the base. A wheel base portion connects the base to the ogive forming a solid core. A polymer jacket encloses at least the wheel base portion of the core and defines an outer diameter that is substantially equal to an outer diameter for a given caliber of bullet.

In further embodiments, the core may also include an annular undercut defined at the proximal end of the ogive and extending into the wheel base portion. The polymer jacket is engaged to the annular undercut to enclose the wheel base portion. In some embodiments, the forward end of the polymer jacket may be extended past the annular undercut to engage a portion of the ogive. The polymer jacket preferably smoothly transitions into the ogive.

In some embodiments, the annular undercut may extend fully to the rearward end. The base may include a boattail tapering into the base. The polymer jacket may extend fully to the rearward end so that a proximal end of the polymer jacket tapers into the distal end of the boattail. The boattail may thus be formed of both polymer material and the metal from the core. Preferably, the polymer jacket smoothly transitions into the distal end of the boattail.

In some embodiments, the rearward end of the metallic core forms a boattail. The polymer jacket may form a distal end of the boattail. Preferably, the polymer jacket smoothly transitions into the boattail. Such embodiments may also include an annular undercut defined in the ogive and extending to the boattail. The polymer jacket encloses the annular undercut from the ogive to the boattail.

In some embodiments, methods for manufacturing hybrid projectiles according to the present invention are disclosed. In one embodiment, the method may involve first machining a metallic core to form the ogive region tapering into the nose. The rearward end of the core tapers into a boattail forming the base. A wheel base portion connects the ogive to the boattail. Next, a polymer jacket is molded over the core to enclose at least the wheel base portion. The polymer jacket defines an outer diameter that is substantially equal to a standard outer diameter for a given caliber of bullet. In some embodiments, the metallic core may be machined to have external dimensions substantially equal to a first caliber bullet. The molding step forms an outer diameter of the polymer jacket that is substantially equal to a standard outer diameter for a second caliber bullet that is larger than the first caliber bullet with which the metallic core has been machined to match.

In alternative embodiments, the method may also include, after the machining step, undercutting annularly the wheel base portion of the metallic core. The annular undercut extends from the distal end of the boattail to a proximal end of the ogive region. In preferred embodiments, the polymer jacket is molded to smoothly transition from the ogive region into the jacket and from the jacket into the boattail.

These and other aspects of the present invention will become apparent to the skilled artisan in view of the following disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. Component parts shown in the drawings are not necessarily to scale, and may be exaggerated to better illustrate the important features of the invention. Dimensions shown are exemplary only. In the drawings, like reference numerals may designate like parts throughout the different views, wherein:

FIG. 1 is a side view of a first embodiment of a hybrid projectile according to the present invention.

FIG. 2 is a cross-sectional view, taken along lines A-A marked in FIG. 1, of an embodiment of a hybrid projectile according to the present invention.

FIG. 3 is a side view of a second embodiment of a hybrid projectile according to the present invention.

FIG. 4 is a cross-sectional view, taken along lines B-B marked in FIG. 3, of an the second embodiment of a hybrid projectile according to the present invention.

FIG. 5 is a flow chart diagramming salient steps of a method for manufacturing a hybrid projectile according to the present invention.

FIG. 6 is a flow chart diagramming salient steps of a second method for manufacturing a hybrid projectile according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following disclosure presents exemplary embodiments of hybrid projectiles according to the present invention. The hybrid projectiles disclosed herein can be manufactured in virtually any caliber of projectile for pistol, rifle or shotgun firearms of military or civilian grade. The hybrid projectiles disclosed herein have a reduced overall weight when compared to a standard metal projectile of equivalent caliber.

Throughout this disclosure, the term “polymer” shall be interpreted in a non-limiting fashion and given a broad interpretation according to its plain and ordinary meaning. “Polymer” can thus mean a natural polymer or a synthetic polymer, and any invention described herein that refers to a “polymer” may be a natural polymer or a synthetic polymer. Examples of polymers as used herein include, but are not limited to, acrylic, polyethylene, polyolefin, polypropylene, polystyrene, polyvinylchloride, synthetic rubber, phenol formaldehyde, neoprene, nylon, polyacrylonitrile, PVB, silicone, and any of the foregoing in powdered, micronized powdered, or resin form.

The hybrid projectiles according to the present invention have several advantages over prior art jacketed projectiles. One such advantage is found in that polymer does not generate the same levels of kinetic heat transfer to the firearm barrel in comparison to traditional metal jacketed bullets. The reduction of heat transfer can reduce wear on the barrel and thereby prolong the life of the firearm and reduce maintenance requirements thereof. Further, polymer can act as a lubricant for a bullet traveling through a firearm barrel, reducing or eliminating material deposits that might otherwise be left behind by a conventional metal bullet. Polymer is also less expensive than metal and therefore use of polymer in the hybrid projectile can reduce the manufacturing costs. A further advantage is found in the reduction to projectile weight achieved by using polymer materials in the jacket. In general, polymer materials weigh less than metal and therefore utilizing polymer to form at least part of the jacket reduces the overall weight for an individual projectile in comparison to a conventional metal jacketed projectile. Reducing the weight for a projectile in a given caliber can result in an increase to the ballistic performance of that projectile. The lighter-weight hybrid projectile according to the present invention can be fired at higher velocities, utilizing the same payload for a conventional bullet of the same caliber, providing for increased accuracy on target.

Note, aspects of the drawings have been exaggerated to aid the reader in better understanding the invention.

FIG. 1 is a side view of a first embodiment of a hybrid projectile according to the present invention. The hybrid projectile 10 includes a core 12 at least partially enclosed by a polymer jacket 14. The forward end 16 includes an ogive 18 tapering into a nose 20. The nose 20 may be formed as a rounded, pointed-tip, blunt nose, and hollow point nose, as is known in the art of ammunition projectiles. The rearward end 22 includes a boattail 24 tapering into the base 26. The polymer jacket 14 extends from the ogive 18 to the boattail 24. The outer surface of the polymer jacket 14 forms the bearing surface 28 which defines the maximum outer diameter of the hybrid projectile 10. The bearing surface 28 is the part of the hybrid projectile 10 that engages the lands and grooves of a firearm barrel as the projectile is discharged therefrom. The outer diameter of the bearing surface 28 thus determines the caliber of the hybrid projectile 10.

FIG. 2 is a cross-sectional view, taken along lines A-A of FIG. 1, of an embodiment of a hybrid-jacketed projectile according to the present invention. In preferred embodiments, the core 12 is dimensioned according to the requirements for a standard projectile in a first caliber. The core 12 may therefore be referred to as a first-caliber core 12. The first-caliber core 12 includes a wheel base portion 30 connecting the ogive 18 to the base 26. The ogive 18 and the base 26 are formed by the first-caliber core 12. The wheel base portion 30 defines a diameter that is dependent on the caliber of the first-caliber core 12.

The polymer jacket 14 encloses at least the wheel base portion 30 of the first-caliber core 12. The distal end 32 of the polymer jacket 14 defines a transition point where ogive 18 smoothly transitions into the polymer jacket. Similarly, the proximal end 34 of the polymer jacket 14 defines a transition point where the polymer jacket smoothly transitions into the boattail 24. Note, as used herein the phrase “smoothly transition” is to be understood to mean there are no corners or abrupt edges or protrusions so there is a sleek transition from one material to the other material to provide a streamlined outer surface.

The smooth transition from the ogive 18 into the polymer jacket 14 is achieved by controlling the angle between the distal end 32 of the jacket 14 and the proximal end of the ogive 18. This angle may be altered by modifying the forward transition plane 36 so that the transition into the bearing surface 28 is more gradual, making the angle more obtuse. In contrast, the smooth transition from the polymer jacket 14 into the boattail 24 is achieved by matching an angle of the rearward transition plane 38 to the angle of the boattail 24.

The hybrid projectile 10 possesses improved ballistic characteristics when compared to a conventional bullet of the same caliber, where the caliber of the hybrid projectile 10 is determined by the outer diameter of the bearing surface 28 formed by the polymer jacket 14. The hybrid projectile 10 has less weight than a conventional bullet of the same caliber and therefore can be propelled at higher velocities utilizing the same payload designed for that conventional bullet. In one example, the first-caliber core 12 may be a conventional 7 mm bullet having a maximum outer diameter substantially equal to 0.284 inches. The hybrid projectile 10 may be equivalent to a .308 caliber bullet, which requires the maximum outer diameter to be substantially equal to 0.308 inches. The polymer jacket 14 therefore has a maximum radial thickness substantially equal to 0.012 inches so that the maximum outer diameter defined by the bearing surface 28 is substantially equal to 0.308 inches. Note, the radial thickness of the polymer jacket 14 throughout the forward transition plane 26 will vary depending on the length thereof. Similarly, the radial thickness of the rearward transition plane 38 varies throughout its length.

In some embodiments, the outer surface of the first-caliber core 12 may be textured to ensure sufficient adherence of the polymer jacket 14 thereto. More specifically, the outer surface of the wheel base portion 30 of the first-caliber core 12 is preferably textured to ensure proper adherence of the polymer jacket 14 thereto. In some embodiments, knurling may be utilized to texture the wheel base portion 30 of the first-caliber core 12 to ensure proper adherence of the polymer jacket 14 thereto.

FIG. 3 is a side view of an alternative embodiment of a hybrid projectile according to the present invention. The hybrid projectile 50 similarly includes a core 52 at least partially enclosed by a polymer jacket 54. The core 52 includes an ogive 56 tapering into the nose 58. Similarly, the rearward end of the core 52 includes a boattail 60 tapering into the base 62. The outer surface of the polymer jacket 54 forms the bearing surface 64, which is the largest diameter section of the hybrid projectile 50 and defines the caliber thereof.

FIG. 4 is a cross-sectional view of an embodiment of the hybrid projectile, taken along lines B-B marked in FIG. 3. The core 52 includes an annular undercut 66 defined in the ogive 56 and extending toward the base 62. Preferably, the annular undercut 66 starts at a proximal end 57 of the ogive 56 and extends through the distal end 61 of the boattail 60. The annular undercut 66 forms a reduced wheel base portion 68 connecting the nose 58 to the base 62. The reduced wheel base portion 68 has a substantially constant diameter defined by the annular undercut 66. The polymer jacket 54 is engaged to the reduced wheel base portion 68 throughout the length of the annular undercut 66 to form the bearing surface 64 in a desired caliber.

In preferred embodiments, the polymer jacket 54 smoothly transitions, as that phrase has been defined herein, into the ogive 56 so that the hybrid projectile 50 maintains its sleek profile. The forward end 70 of the polymer jacket 54 may taper smoothly into the proximal end 57 of the ogive 56. In alternative embodiments, the radial thickness of the forward end 70 of the polymer jacket 54 may be substantially equal to the depth of the annular undercut 66 so that the proximal end 57 of the ogive 56 smoothly transitions into the polymer jacket 54.

The rearward end 72 of the polymer jacket 54 tapers inward at the same degree with which the boattail 60 tapers into the base 62 to provide a smooth transition from the polymer jacket 54 into the boattail 60 portion of the core 52. The boattail 60 may be comprised of metal material from the core 52 in addition to polymer material from the polymer jacket 54. In alternative embodiments, the annular undercut 66 may extend only to the distal end 61 of the boattail 60 so that the polymer jacket 54 extends from the boattail 60 to the ogive 56. In such embodiments, the boattail 60 would be fully formed from the metal material of the core 52.

In one example, the core 52 of the hybrid projectile 50 may start as a conventional solid metal bullet dimensioned according to the requirements of a given caliber. The solid metal bullet may be a .308 caliber bullet so that the initial maximum outer diameter is substantially equal to 0.308 inches. The annular undercut 66 is applied to the core 52, starting at the ogive 56 and extending through the boattail 60, to form the reduced wheel base portion 68. The annular undercut 66 may reduce the diameter of the reduced wheel base portion 68 by about 0.010 inches so that the diameter of the reduced wheel base portion 68 is substantially equal to about 0.298 inches, e.g., radial thickness of the reduced wheel base portion 68 is uniformly reduced by about 0.005 inches. The polymer jacket 54 is thereafter applied to the reduced wheel base portion 68 to grow the outer diameter to a diameter required for the desired caliber. In the present example, the polymer jacket 54 may have a radial thickness substantially equal to 0.005 inches so that the bearing surface 64 has a maximum outer diameter substantially equal to 0.308 inches to satisfy the requirements for a .308 caliber bullet. The hybrid projectile 50 will weigh less than a conventional bullet of the same caliber and therefore achieve higher velocities using the same payload.

FIG. 5 is a flow chart diagramming the salient steps for a first embodiment of a method for manufacturing a hybrid projectile according to the present invention. Method 100 may be particularly useful for manufacturing the hybrid projectile 10 described above. The method 100 begins with forming the core 12 at step 102. Step 102 may involve machining a solid metal bar stock into a first-caliber core 12, having dimensions substantially equal to those required for a standard bullet of that caliber. For example, the first-caliber core 12 may be formed by machining solid copper bar stock into a standard 7 mm bullet. Preferably, the machining process involved in step 102 is accomplished on a computer numerical control (CNC) lathe machine to precisely form the first-caliber core 12. In alternative embodiments, step 102 may involve metal injection molding the first-caliber core 12 according to conventional injection molding techniques. In further alternative embodiments, the first-caliber core 12 may be formed at step 102 by compressing one or more metal powders into the required form.

Once the first-caliber core 12 has been formed, the core is suspended in a mold at step 104 and thereafter the polymer jacket 14 is molded over the core 12 at step 106. More specifically, at step 106 the polymer jacket 14 is molded to enclose the wheel base portion 30 of the first-caliber core 12. The polymer jacket 14 is molded in sufficient quantity so that the diameter of the bearing surface 28 is substantially equal to a standard outer diameter for a second caliber. The molding step 106 therefore grows the first-caliber core 12 into the larger caliber hybrid projectile 10. The final step 108 simply requires removal of the hybrid projectile 10 from the mold.

FIG. 6 is a flow chart diagramming the salient steps for an alternative method for manufacturing a hybrid projectile according to the present invention. The method 200 is particularly useful for manufacturing the hybrid projectile 50 described above. The method 200 similarly begins with forming the core 52 at step 202. The core 52 is preferably dimensioned according to the requirements for a given caliber of bullet. In some preferred embodiments, step 202 may involve machining the core 52 on a CNC lathe machine. In alternative embodiments, step 202 may involve compressing one or more metal powders to form the core 52 or metal injection molding the core.

Once the core 52 is formed at step 202, the wheel base portion is undercut annularly at step 204 to form the reduced wheel base portion 68. Preferably, step 204 is performed on a CNC lathe machine to precisely form the reduced wheel base portion 68. The annular undercut 66 extends from the ogive 56 through the boattail 60 so that the reduced wheel base portion 68 has a substantially constant outer diameter. The amount of core material removed during the undercutting step 204 depends on the caliber the core 52 is first formed to in step 202 and the final desired caliber for the hybrid projectile 50. Where the core 52 is formed into a .308 caliber bullet in step 202, step 204 may involve undercutting the wheel base portion of the core down to a diameter substantially equal to about 0.298 inches, e.g., remove 0.005 inches radial thickness from the wheel base portion.

Step 206 involves suspending the undercut core, e.g., core 52, in a mold. At step 208 the polymer jacket 54 is molded over the undercut core. The polymer jacket 54 is molded according to conventional injection molding techniques. More specifically, at step 208 the polymer jacket 54 is molded to enclose the reduced wheel base portion 68, extending from the proximal end 57 of the ogive 56 to the distal end 61 of the boattail 60. The polymer jacket 54 is molded so that there is a smooth transition from the ogive 56 into the polymer jacket 54 and from the jacket into the boattail 60. The radial thickness of the polymer jacket 54 depends on several factors, including the desired final caliber of the hybrid projectile 50 and the diameter of the reduced wheel base portion 68 resulting from step 204. In the above example, the polymer jacket 54 may be molded at step 208 with a radial thickness substantially equal to 0.005 inches so the diameter of the bearing surface 64 is substantially equal to 0.308 inches. Thus, the hybrid projectile 50 in this example is a hybrid .308 bullet.

In alternative embodiments, the polymer jacket 54 may be molded with a radial thickness sufficient to form a bearing surface 64 equal to a caliber larger than the starting caliber of the core 52 resulting from step 202. For example, the core 52 resulting from step 202 may be formed according to the requirements of a .308 caliber bullet while the desired caliber for the final hybrid projectile 50 is a .338 caliber bullet. The undercutting step 204 may remain unchanged so that the annular undercut 66 forms a reduced wheel base portion 68 having a diameter substantially equal to 0.298 inches. The molding step 208 thereafter involves molding the polymer jacket 54 with sufficient material to build up the outer diameter of the bearing surface 64 to be substantially equal to 0.338 inches. Thus, the radial thickness of the polymer jacket 54 may be substantially equal to 0.020 inches so that the diameter of the bearing surface 64 is substantially equal to 0.338 inches. The final projectile that is removed from the mold at step 210 would therefore be a hybrid .338 caliber bullet. In this example, the hybrid .338 caliber bullet is lighter than a standard .338 caliber bullet and thus can achieve higher velocities using the same payload. This translates into a flatter flight path to the intended target, thereby increasing the accuracy of the projectile.

Exemplary embodiments of the invention have been disclosed in an illustrative style. Accordingly, the terminology employed throughout should be read in a non-limiting manner. Although minor modifications to the teachings herein will occur to those well versed in the art, it shall be understood that what is intended to be circumscribed within the scope of the patent warranted hereon are all such embodiments that reasonably fall within the scope of the advancement to the art hereby contributed, and that that scope shall not be restricted, except in light of the appended claims and their equivalents.