Hybrid Projectile

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

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.

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.

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.

is a side view of a first embodiment of a hybrid projectile according to the present invention. The hybrid projectileincludes a coreat least partially enclosed by a polymer jacket. The forward endincludes an ogivetapering into a nose. The nosemay be formed as a rounded, pointed-tip, blunt nose, and hollow point nose, as is known in the art of ammunition projectiles. The rearward endincludes a boattailtapering into the base. The polymer jacketextends from the ogiveto the boattail. The outer surface of the polymer jacketforms the bearing surfacewhich defines the maximum outer diameter of the hybrid projectile. The bearing surfaceis the part of the hybrid projectilethat engages the lands and grooves of a firearm barrel as the projectile is discharged therefrom. The outer diameter of the bearing surfacethus determines the caliber of the hybrid projectile.

is a cross-sectional view, taken along lines A-A of, of an embodiment of a hybrid-jacketed projectile according to the present invention. In preferred embodiments, the coreis dimensioned according to the requirements for a standard projectile in a first caliber. The coremay therefore be referred to as a first-caliber core. The first-caliber coreincludes a wheel base portionconnecting the ogiveto the base. The ogiveand the baseare formed by the first-caliber core. The wheel base portiondefines a diameter that is dependent on the caliber of the first-caliber core.

The polymer jacketencloses at least the wheel base portionof the first-caliber core. The distal endof the polymer jacketdefines a transition point where ogivesmoothly transitions into the polymer jacket. Similarly, the proximal endof the polymer jacketdefines a transition point where the polymer jacket smoothly transitions into the boattail. 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 ogiveinto the polymer jacketis achieved by controlling the angle between the distal endof the jacketand the proximal end of the ogive. This angle may be altered by modifying the forward transition planeso that the transition into the bearing surfaceis more gradual, making the angle more obtuse. In contrast, the smooth transition from the polymer jacketinto the boattailis achieved by matching an angle of the rearward transition planeto the angle of the boattail.

The hybrid projectilepossesses improved ballistic characteristics when compared to a conventional bullet of the same caliber, where the caliber of the hybrid projectileis determined by the outer diameter of the bearing surfaceformed by the polymer jacket. The hybrid projectilehas 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 coremay be a conventional 7 mm bullet having a maximum outer diameter substantially equal to 0.284 inches. The hybrid projectilemay be equivalent to a .308 caliber bullet, which requires the maximum outer diameter to be substantially equal to 0.308 inches. The polymer jackettherefore has a maximum radial thickness substantially equal to 0.012 inches so that the maximum outer diameter defined by the bearing surfaceis substantially equal to 0.308 inches. Note, the radial thickness of the polymer jacketthroughout the forward transition planewill vary depending on the length thereof. Similarly, the radial thickness of the rearward transition planevaries throughout its length.

In some embodiments, the outer surface of the first-caliber coremay be textured to ensure sufficient adherence of the polymer jacketthereto. More specifically, the outer surface of the wheel base portionof the first-caliber coreis preferably textured to ensure proper adherence of the polymer jacketthereto. In some embodiments, knurling may be utilized to texture the wheel base portionof the first-caliber coreto ensure proper adherence of the polymer jacketthereto.

is a side view of an alternative embodiment of a hybrid projectile according to the present invention. The hybrid projectilesimilarly includes a coreat least partially enclosed by a polymer jacket. The coreincludes an ogivetapering into the nose. Similarly, the rearward end of the coreincludes a boattailtapering into the base. The outer surface of the polymer jacketforms the bearing surface, which is the largest diameter section of the hybrid projectileand defines the caliber thereof.

is a cross-sectional view of an embodiment of the hybrid projectile, taken along lines B-B marked in. The coreincludes an annular undercutdefined in the ogiveand extending toward the base. Preferably, the annular undercutstarts at a proximal endof the ogiveand extends through the distal endof the boattail. The annular undercutforms a reduced wheel base portionconnecting the noseto the base. The reduced wheel base portionhas a substantially constant diameter defined by the annular undercut. The polymer jacketis engaged to the reduced wheel base portionthroughout the length of the annular undercutto form the bearing surfacein a desired caliber.

In preferred embodiments, the polymer jacketsmoothly transitions, as that phrase has been defined herein, into the ogiveso that the hybrid projectilemaintains its sleek profile. The forward endof the polymer jacketmay taper smoothly into the proximal endof the ogive. In alternative embodiments, the radial thickness of the forward endof the polymer jacketmay be substantially equal to the depth of the annular undercutso that the proximal endof the ogivesmoothly transitions into the polymer jacket.

The rearward endof the polymer jackettapers inward at the same degree with which the boattailtapers into the baseto provide a smooth transition from the polymer jacketinto the boattailportion of the core. The boattailmay be comprised of metal material from the corein addition to polymer material from the polymer jacket. In alternative embodiments, the annular undercutmay extend only to the distal endof the boattailso that the polymer jacketextends from the boattailto the ogive. In such embodiments, the boattailwould be fully formed from the metal material of the core.

In one example, the coreof the hybrid projectilemay 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 undercutis applied to the core, starting at the ogiveand extending through the boattail, to form the reduced wheel base portion. The annular undercutmay reduce the diameter of the reduced wheel base portionby about 0.010 inches so that the diameter of the reduced wheel base portionis substantially equal to about 0.298 inches, e.g., radial thickness of the reduced wheel base portionis uniformly reduced by about 0.005 inches. The polymer jacketis thereafter applied to the reduced wheel base portionto grow the outer diameter to a diameter required for the desired caliber. In the present example, the polymer jacketmay have a radial thickness substantially equal to 0.005 inches so that the bearing surfacehas a maximum outer diameter substantially equal to 0.308 inches to satisfy the requirements for a .308 caliber bullet. The hybrid projectilewill weigh less than a conventional bullet of the same caliber and therefore achieve higher velocities using the same payload.

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. Methodmay be particularly useful for manufacturing the hybrid projectiledescribed above. The methodbegins with forming the coreat step. Stepmay involve machining a solid metal bar stock into a first-caliber core, having dimensions substantially equal to those required for a standard bullet of that caliber. For example, the first-caliber coremay be formed by machining solid copper bar stock into a standard 7 mm bullet. Preferably, the machining process involved in stepis accomplished on a computer numerical control (CNC) lathe machine to precisely form the first-caliber core. In alternative embodiments, stepmay involve metal injection molding the first-caliber coreaccording to conventional injection molding techniques. In further alternative embodiments, the first-caliber coremay be formed at stepby compressing one or more metal powders into the required form.

Once the first-caliber corehas been formed, the core is suspended in a mold at stepand thereafter the polymer jacketis molded over the coreat step. More specifically, at stepthe polymer jacketis molded to enclose the wheel base portionof the first-caliber core. The polymer jacketis molded in sufficient quantity so that the diameter of the bearing surfaceis substantially equal to a standard outer diameter for a second caliber. The molding steptherefore grows the first-caliber coreinto the larger caliber hybrid projectile. The final stepsimply requires removal of the hybrid projectilefrom the mold.

is a flow chart diagramming the salient steps for an alternative method for manufacturing a hybrid projectile according to the present invention. The methodis particularly useful for manufacturing the hybrid projectiledescribed above. The methodsimilarly begins with forming the coreat step. The coreis preferably dimensioned according to the requirements for a given caliber of bullet. In some preferred embodiments, stepmay involve machining the coreon a CNC lathe machine. In alternative embodiments, stepmay involve compressing one or more metal powders to form the coreor metal injection molding the core.

Once the coreis formed at step, the wheel base portion is undercut annularly at stepto form the reduced wheel base portion. Preferably, stepis performed on a CNC lathe machine to precisely form the reduced wheel base portion. The annular undercutextends from the ogivethrough the boattailso that the reduced wheel base portionhas a substantially constant outer diameter. The amount of core material removed during the undercutting stepdepends on the caliber the coreis first formed to in stepand the final desired caliber for the hybrid projectile. Where the coreis formed into a .308 caliber bullet in step, stepmay 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.

Stepinvolves suspending the undercut core, e.g., core, in a mold. At stepthe polymer jacketis molded over the undercut core. The polymer jacketis molded according to conventional injection molding techniques. More specifically, at stepthe polymer jacketis molded to enclose the reduced wheel base portion, extending from the proximal endof the ogiveto the distal endof the boattail. The polymer jacketis molded so that there is a smooth transition from the ogiveinto the polymer jacketand from the jacket into the boattail. The radial thickness of the polymer jacketdepends on several factors, including the desired final caliber of the hybrid projectileand the diameter of the reduced wheel base portionresulting from step. In the above example, the polymer jacketmay be molded at stepwith a radial thickness substantially equal to 0.005 inches so the diameter of the bearing surfaceis substantially equal to 0.308 inches. Thus, the hybrid projectilein this example is a hybrid .308 bullet.

In alternative embodiments, the polymer jacketmay be molded with a radial thickness sufficient to form a bearing surfaceequal to a caliber larger than the starting caliber of the coreresulting from step. For example, the coreresulting from stepmay be formed according to the requirements of a .308 caliber bullet while the desired caliber for the final hybrid projectileis a .338 caliber bullet. The undercutting stepmay remain unchanged so that the annular undercutforms a reduced wheel base portionhaving a diameter substantially equal to 0.298 inches. The molding stepthereafter involves molding the polymer jacketwith sufficient material to build up the outer diameter of the bearing surfaceto be substantially equal to 0.338 inches. Thus, the radial thickness of the polymer jacketmay be substantially equal to 0.020 inches so that the diameter of the bearing surfaceis substantially equal to 0.338 inches. The final projectile that is removed from the mold at stepwould 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.