Patent Application
20240377173
None.
The present invention relates generally to ammunition for firearms, and more specifically to jacketed projectiles designed to resist mid-flight disintegration.
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.
No matter the type of projectile, the spin rate, or revolutions per minute (RPM), of the projectile directly affects the performance and integrity during flight. High levels of RPM can increase accuracy and overall performance of the projectile. In some firearm systems, the projectile can achieve RPMs upwards of 300,000. This high ballistic performance can be desirable for military and law enforcement use as well as certain civilian uses, such as for competition shooting and hunting.
A problem that can occur in jacketed projectiles at high levels of RPM is the jacket and the projectile core can begin to spin at different RPMs. At such high RPMs, when the jacket and core begin spinning at different rates, the projectile can disintegrate mid-flight. That is, the core and the jacket can separate from one another mid-flight and become completely destroyed. The disintegration of the projectile may occur at any point along the flight path once the RPM of the core has deviated sufficiently from the RPM of the jacket.
The problem of the disintegrating projectile is not limited to projectiles with conventional metal jackets but may also occur when the jacket is made from a polymer material as well. Regardless of the jacket material, an unbalanced core may result in differing RPMs between the core and the jacket. Also, it is not uncommon for a core to be lubricated prior to application of a jacket thereon. However, any remaining lubrication may result in the core coming loose from the jacket and thus spinning at a different RPM than the jacket.
For obvious reasons, a projectile that disintegrates prior to reaching the desired target will be ineffective. Disintegrating projectiles also pose a significant risk to bystanders if the projectile is used during military or law enforcement activities where it is not uncommon for bystanders to be downrange from a shooter. A projectile that disintegrates mid-flight may send shrapnel flying in different directions which could injure bystanders.
Thus, what is needed is a jacketed projectile with a core designed specially to lock onto the surrounding jacket so as to decrease the likelihood of there being any variance in the RPM of the jacket and the core.
The invention herein relates to a jacketed projectile and methods of manufacturing the jacketed projectile. In preferred embodiments, the jacket is made from a polymer material and applied over the core in an injection molding process. However, other materials may be used for the jacket, such as conventional brass or copper jackets.
In accordance with one embodiment of the invention, a projectile core has at least one key defined in an outer surface thereof. The key is a recessed portion and is configured to provide a mating surface for receiving additional material of the jacket that is applied over the outer surface of the core. The increase in thickness of the jacket material at the key on the core increases adherence between the core and the jacket. The increased adherence between the materials, in turn, increases resistance to the jacket and core spinning at different RPMs and thus separating at high levels of RPMs.
Preferably, the jacket is composed of a polymer material that is molded over the core. The polymer material of the jacket flows into the key to lock the jacket onto the core.
The jacketed projectile can be made in essentially any projectile shape and for any caliber of firearm. The key in some embodiments is designed as a circumferential groove defined in the outer surface of the ogive region. The jacket material fills the groove to lock the jacket and core together and thus resist separation during flight. The projectile core may have multiple keys configured as circumferential grooves to further increase engagement between the jacket and the core. The key is designed such that rotational symmetry of the projectile is preserved when the jacket is molded over the core to ensure proper balance is maintained in the final keyed jacketed projectile.
Alternatively, the key may be a circular groove defined in the outer surface of the core. In some embodiments, the circular groove may extend substantially through the core from a first side to the opposite side. The corresponding thickened section of the jacket will also extend substantially through the core to form a bridge through the core from a first side of the jacket to the opposite side. In yet other embodiments, the key may be configured as an axial groove defined in the outer surface of the core and extending a length from a tip region to a base region. In embodiments utilizing the axial groove, it may be necessary to include a second axial groove substantially opposite the first axial groove. The purpose of the opposing axial grooves is to ensure the projectile has rotational symmetry and maintains proper balance. Alternatively, there may be a plurality of axial grooves defined in the outer surface that are spaced equidistance from one another.
In yet more alternative embodiments, the key may be any one of a circular groove, circumferential grooves, axial grooves, and/or any combination thereof. Any of the circular grooves, circumferential grooves and axial grooves may be defined in virtually any position around the projectile core. The depth of the grooves, whether it be a circular, circumferential or axial groove, is controlled such that there is a secure engagement between the core and the jacket while also maintaining proper balance.
The number and dimensions of the key(s) on the core are caliber and performance characteristics dependent. Meaning, depending on the size of projectile caliber and the terminal ballistic characteristics desired, a certain key configuration and/or combination thereof may be more desirable than others.
In some embodiments, the projectile core may be a core equivalent to a first caliber projectile, e.g., a 7 mm caliber projectile. The core may be formed from powdered metals or can be a conventional projectile of that caliber. The key may be molded, machined or otherwise formed in the outer surface of the first caliber core. A jacket is then applied over the first caliber core in sufficient quantity to bring the outer dimensions of the projectile into compliance with a second caliber projectile, e.g., a 0.308 caliber projectile, and completely fill the key(s) defined in the outer surface of the core. The engagement of the jacket to the core at the key ensures the two components are locked together, which thereby increases the relative resistance to separation at high RPMs.
The jacketed projectile may be formed to meet the specifications of any standard bullet or other standardized projectile shape. For instance, the jacketed projectile may be formed for rifle ammunition having a defined ogive and boat tail or may be formed with a flat base for pistol ammunition. Alternatively, the inventive concepts can also be applied to pellets or to shot used in shotgun ammunition and to projectiles used in large caliber artillery weapons. Similarly, the jacket may be molded to form a hollow point projectile or a rounded or pointed tip projectile.
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:
The following disclosure presents exemplary embodiments of a keyed jacketed projectile. In specific embodiments disclosed, the jacketed projectile has a core that is overmolded with a polymer jacket. The core has at least one key configured defined in an outer surface thereof for receiving an additional thickness of the polymer jacket material. The jacketed projectiles disclosed herein are suitable for the construction of a projectile fired from a pistol, rifle, or shotgun of military or civilian grade. Also disclosed are methods for manufacturing the disclosed keyed jacketed projectile.
Throughout this disclosure, the terms “polymer” and “synthetic polymer” and “synthetic coating” shall be interpreted in a non-limiting fashion and given a broad interpretation according to their plain and ordinary meaning. “Polymer” can mean a natural polymer or a synthetic polymer, and any invention described herein that refers to a “synthetic polymer” may, in an alternative embodiment, substitute a natural polymer for the synthetic polymer and vice versa. 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 keyed jacketed projectile according to the present invention has several advantages over prior art jacketed projectiles. One such advantage is found in that polymer does not generate the same levels of kinetic heat as that of more traditional copper jackets. Thus, the polymer jacketed projectile has less heat transferred to the barrel of the weapons system, which can prolong the life of the barrel and reduce maintenance requirements. Further, polymer is less expensive than the metals traditionally used for jacketing projectiles and therefore can reduce manufacturing costs. A third advantage is found in weight savings regarding the projectile weight. In general, a polymer jacketed projectile according to the present invention weighs less than a metal jacketed projectile of the same caliber. The overall reduction in weight results in improved ballistic performance of the projectile. As will become apparent to the skilled artisan, jacketing a keyed projectile in a polymer jacket has numerous other advantages over the prior art beyond those described herein.
The keyed projectile core may be made from conventional projectile materials, such as lead. With a lead core, the one or more keys may be machined into the outer surface of the core. Alternatively, and more preferably, the keyed core is formed from metal powders according to conventional metal injection molding processes. The metal powder chosen preferably has a density greater than lead, such as is characteristic of tungsten. Depending on the desired density and weight of the core, it may be necessary to add one or more filler materials, such as tin, zinc or aluminum. The choice of primary core material and filler material may be utilized as a means to control the desired characteristics of the core, such as density, weight and frangibility upon impact with a target. Further, use of polymer materials for the jacket more readily ensures that the jacket completely fills the key defined in the keyed core during the molding process. This ensures the keyed core and jacket are sufficiently locked together such that the two components co-rotate about a common axis during flight. The co-rotation of the keyed core with the jacket increases the resistance to rotational separation or projectile disintegration during flight. These and other advantages according to the present invention will become readily apparent to the skilled artisan in the following descriptions.
As used herein, the term “key” or “keyed” is understood to mean a groove or recessed portion defined in the outer surface of the projectile core. The key 12 can be configured as any one of a circumferential groove, a circular groove, an axial groove, or any combination thereof where multiple keys are used. As explained in more detail below, the jacket 16 has a thickened section which corresponds to and substantially fills the key defined in the core. The thickened section of the jacket locks the jacket onto the core to ensure the jacket and core co-rotate about a common axis during flight. The locked co-rotation of the core and the jacket increases resistance to rotational separation during flight, especially at extremely high levels of RPMs. In some embodiments, an adhesive may be applied to the key prior to being covered with the jacket. Use of an adhesive increases the strength of the connection between the core and jacket and thereby further increases the resistance to rotational separation during flight.
The key 12 is designed to be symmetrical within the keyed core such that the final jacketed projectile has rotational symmetry about its longitudinal axis. Maintaining rotational symmetry in the core ensures that when the jacket 16 is molded over the core, the final keyed jacketed projectile is properly balanced. Proper balance of the jacketed projectile is essential to ensuring consistency of the terminal ballistics of the projectile from round to round. Unbalanced projectiles have decreased accuracy and velocity and thus are undesirable to shooters. Therefore, ensuring the key 12 is symmetrical about the keyed core to maintain rotational symmetry in the keyed jacketed projectile is an essential component of the present invention.
The keyed jacketed projectile 100 can be formed with an ogive region 20. As is conventional for ammunition projectiles, the ogive region 20 is a forward end of the projectile that includes an inward taper toward a longitudinal centerline of the projectile. In some embodiments, the keyed jacketed projectile 100 can also have a boat tail region 18 opposite the ogive region to define a base end 30. The tip end 28 may be designed as a hollow point, rounded nose and/or pointed tip, as is conventional for ammunition projectiles. Defined substantially between the ogive region 20 and the boat tail region 18 is a body region 19. The body region 19 defines the largest outer diameter for the keyed jacketed projectile 100. The outer diameter of the body region 19 is largely dependent on the caliber of projectile. Larger calibers will have larger outer diameters at the body region 19 corresponding to the larger internal diameter of barrels used in such weapons systems. The opposite is true for smaller caliber projectiles.
As shown in
The circular grooved keys 212 are recessed inwards into the core 210 such that the circular grooved keys 212 extend a defined depth into the core. The depth may depend on the relative diameter and number of keys 212 used and may further depend on the caliber of projectile. The jacket 16 completely covers the projectile core 210 to form the keyed jacketed projectile 200. The jacket 16 has a thickened section 214 corresponding to the location of the circular grooved keys 212. The thickened section 214 extends the jacket material inward into the core 210 a depth equal to the depth of the key 12 to substantially fill the circular key 212. The thickened section 214 of the jacket 16 works together with the circular grooved key 212 to preserve co-rotation of the keyed core 210 with the jacket 16 during flight and therefore increase resistance to rotational separation during flight.
In alternate embodiments, the circular grooved key 212 may extend substantially through the core 210 from a first side to the opposite side. In such embodiments, the thickened section 214 of the jacket 16 may also extend substantially through the core 210 to form a bridge through the core.
As shown in
In alternate embodiments, there may be a plurality of circumferential grooved keys 412 defined in the outer surface of the keyed core 410. The jacket 16 would similarly have a plurality of thickened sections 414 to substantially fill each corresponding circumferential grooved key 412.
In alternate embodiments of the keyed core 510 having multiple axial grooved keys 512, the jacket 16 similarly has multiple thickened sections 514. Each of the thickened sections 514 corresponds to a respective axial grooved key 512 and substantially fills each key. Ensuring that there is a thickened section of the jacket corresponding to each key maintains proper balance in the final jacketed projectile. Further, spacing each of the keys equidistance from one another helps to maintain rotational symmetry and balance in the final keyed jacketed projectile.
Combining the different key configurations results in an increased connection between the jacket 16 and keyed core 710, which thereby increases resistance to rotational separation during flight. The final projectile using keyed core 710 (or any sub-variation of the combination of keys 12) may be advantageous for certain long-range projectiles where the RPM and velocity of the projectile are extremely high. Further, the final projectile using keyed core 710 may be more advantageous for certain types of projectiles that have significant mass, for instance certain types of artillery rounds. Use of a combination of the differing key configurations may aid in maintaining proper balance in the final projectile.
In alternative embodiments of the manufacturing method, step 602 may comprise providing a core of a first, undersized, caliber that has already been properly balanced. For instance, a properly balanced 7 mm projectile may be used as the core. The keys are thereafter machined into the outer surface of the projectile. At step 606, molding the jacket may comprise molding a jacket having a thickness sufficient to bring the dimensions of the first undersized core up to the dimensions of a second, large caliber projectile, e.g., a 0.308 caliber projectile. In the example of molding a 7 mm projectile used as the core up to a 0.308 keyed projectile, the jacket can be molded with a thickness substantially equal to 0.012 inches thick, notwithstanding the thickened portions of the jacket which fill the one or more keys of the core. The process thereafter continues normally.
These and other variations on the method 600 will become apparent to the skilled artisan and are fully encompassed by the present disclosure. The method 600 has been described in stepwise fashion but the skilled artisan will understand that many of the steps can be performed simultaneously.
A jacketed projectile made according to the invention may have a diameter that may vary from about 1.50 mm to about 158.00 mm. Thus, projectiles such as 155 mm artillery rounds are included within the scope of products made by a process according to the invention.
The foregoing description describes and illustrates projectiles having a defined boat tail and ogive region, which are common in rifle projectiles. However, it should be understood that the present invention can be applied equally to all types of projectiles for any type of weapons system, including flat base projectiles common for pistol firearms. Further, the inventive concepts can also be applied to projectiles for other types of ammunition, including pellets or shots used in shotgun ammunition. The final jacketed projectile may also be formed with a hollow point or traditional round or pointed nose.
Projectiles manufactured according to the processes disclosed herein will have lighter and more stable projectile mass, as compared to conventional projectiles. This means that a projectile made according to the present invention may advantageously carry more payload than a conventional projectile and achieve superior performance while simultaneously having an increased resistance to disintegration at high RPM levels. For example, a projectile of the present invention could be fired to achieve RPMs in excess of 300,000 and pack additional fuel (e.g. gunpowder) to achieve longer range, or could pack additional explosive charge in the war head to deliver greater damage without being susceptible to projectile disintegration mid-flight.
While the invention has been described as using a polymer material to form the jacket, it should be understood that conventional metal materials may also be used to form the jacket. The key to using conventional metal materials is to ensure the metal jacket completely fills the key defined in the core to create a locking engagement between the jacket and the core such that projectile is able to resist separation at high RPM levels.
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.
