Self-Separating Bullet

Abstract

Provided is a projectile with one or more structurally weakened zones that break apart into sub-projectiles after firing and prior to muzzle exit. The structurally weakened zones are generally of diminished cross-sectional area and designed to fail as the bullet travels down a rifled barrel. The failure occurs as a result of induced stress states in the structurally weakened zones that exceed material strength of the connective structure between sections of the initially unbroken projectile. The locations of structurally weakened zones can be selected to produce separated sub-projectiles that are of the same / similar or different individual mass, depending on the desired dispersion characteristics for a given application. The inventive self-separating bullet provides projectile multiplication for improved probability of hit per round fired, extended effective range, improved dispersion, and cost savings thanks to the simplicity of the projectile design and associated ease of manufacture.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Patent Application Ser. No. 63 / 667,295, filed Jul. 3, 2024, entitled “SELF-SEPARATING BULLET,” the disclosure of which is expressly incorporated by reference herein.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] The invention described herein was made in the performance of official duties by employees of the Department of the Navy and may be manufactured, used and licensed by or for the United States Government for any governmental purpose without payment of any royalties thereon. This invention (Navy Case 212233) is assigned to the United States Government and is available for licensing for commercial purposes. Licensing and technical inquiries may be directed to the Technology Transfer Office, Naval Surface Warfare Center Crane, email: Crane_T2@navy.mil.FIELD OF THE INVENTION

[0003] The field of invention relates generally to firearm cartridges. More particularly, it pertains to a projectile with one or more structurally weakened zones that breaks apart into sub-projectiles after firing.BACKGROUND

[0004] Unmanned Aerial Systems (UAS), particularly smaller Group 1 and 2 UAS are notoriously difficult to incapacitate using kinetic methods via small arms. As is known, even a direct hit on target does not guarantee incapacitation. One means of overcoming this problem is by increasing the number of projectiles in / around the target, such as by using projectiles that produce two or more sub-projectiles per round fired and / or enabling more dispersed effects about the intended point-of-aim (i.e., creating “shotgun-style” effects). Furthermore, disbursing effects about the point-of-aim can help overcome point-of-aim errors resulting from shooter inexperience, lack of target lead or improper lead (for a moving target), or erratic target flight (where it becomes difficult or impossible to predict target trajectory).

[0005] A variety of multi-projectile cartridge solutions for use in small arms (i.e., long guns other than shotguns) are known and in use, however, these designs provide limited or no success in counter-UAS applications. Examples of multi-projectile cartridges include “duplex” and “triplex” rounds, sometimes also referred to as “multiplex” rounds, which generally incorporate a series of two or three stacked and pointed projectiles in each cartridge to offer projectile multiplication per round fired. These designs, however, generally suffer from lack of projectile dispersion with the stacked individual projectiles being the same or similar in mass and profile along with limited or no axial separation between the flight of individual projectiles. In other words, each individual projectile follows identically or very closely in trajectory to the path of the leading projectile. Designs such as these may inflict greater damage if the target is hit, but the lack of projectile dispersion does not increase the probability of hit, especially when used with basic shoulder-fired weapons lacking advanced optics or fire control capabilities, such as automatic target tracking. Additionally, the individual projectiles of duplex and triplex rounds travel significant distances and cause concerns over collateral damage due to their aerodynamic efficiency. Lastly, multiplex rounds can be expensive to produce due to sub-assembly process steps required to generate the stacked projectile prior to loading.

[0006] Other counter-UAS projectile-multiplying developmental cartridge types for use with small arms utilize a number of sub-caliber spherical projectiles. These sub-caliber projectiles, however, are often not properly stabilized during firing. This is especially true when fired through conventional small arms that have rifled barrels with twist rates designed for bullets used in conventional ball ammunition types. While the use of spherical sub-projectiles can be effective, these designs offers limited effective range and higher projectile assembly and cartridge unit costs.

[0007] As can be seen from the above, a projectile that produces two or more sub-projectiles per round fired that has greater dispersed effects about the intended point-of-aim, increased range, and cost effectiveness is desirable.SUMMARY OF THE INVENTION

[0008] Provided is a projectile with one or more structurally weakened zones that break apart into sub-projectiles after firing and prior to muzzle exit. The structurally weakened zones are generally of diminished cross-sectional area and designed to fail as the bullet travels down a rifled barrel. This desired failure occurs as a result of induced stress states in the structurally weakened zones that exceed material strength of the connective structure between sections of the initially unbroken projectile. As the leading section of the bullet engages the origin of rifling and begins to rotate, the trailing sections of the bullet toward the aft end of the projectile are not yet rotating via direct engagement with the rifling. Rather, their rotation relies on forces communicated through the connective structure at the aft end of the first segment. As a result, a torsional / shear stress component is developed within the structurally weakened zones.

[0009] In addition to the induced stress states, the projectile design allows for the direct impingement of propellant gas pressure on the interior or exterior surfaces of the structurally weakened zones, providing for additional stress contributors, such as compressive stress, hoop / circumferential stress, and longitudinal / axial stress. These additional stresses act in combination to produce even greater combined stress states. The effects of individual stress contributors or combined stresses may then be further enhanced through the implementation of geometric stress concentrators, such as a sharp interior corner in the root of an external groove comprising a portion of the structurally weakened zone. Furthermore, rapidly elevated material temperatures in the structurally weakened zones resulting from direct impingement of hot propellant gasses and / or heat transfer to these regions from hot propellant gases and / or friction between the bullet and barrel rifling further reduce material strength. The application of stress and heat can be utilized to produce the desired separation of the projectile into sub-projectiles at each structurally weakened zone.

[0010] The locations of structurally weakened zones can be selected to produce separated sub-projectiles that are of the same / similar or different individual mass, depending on the desired dispersion characteristics for a given application. The end result produces sub-projectiles that each maintain a portion of its full caliber / diameter outer profile relative to the initially unbroken projectile, allowing for each sub-projectile to directly engage with the barrel rifling even after separation, which ensures sub-projectile stability upon muzzle exit. Additionally, altering individual sub-projectile geometries allows for manipulation of individual sub-projectile trajectories, which can be used to produce desired dispersion patterns and less efficient aerodynamic properties, thereby reducing collateral damage.

[0011] The inventive self-separating bullet provides a simple one-piece design that can be manufactured monolithically from a single material. There are no sub-assembly steps required for the projectile, and it may be readily utilized with conventional cartridge cases, primers, and propellant. The projectile may be reliably and safety fired through existing small arms without any gun part changes. The inventive self-separating bullet provides projectile multiplication for improved probability of hit per round fired, extended effective range, improved dispersion, and cost savings thanks to the simplicity of the projectile design and associated ease of manufacture.

[0012] Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The detailed description of the drawings particularly refers to the accompanying figures in which:

[0014] FIG. 1 shows a side section view of a self-separating bullet.

[0015] FIG. 2 shows a side section view of a self-separating bullet as assembled in a cartridge case.

[0016] FIG. 3A shows a side section view of a self-separating bullet and a cartridge case chambered in a firearm barrel and prior to firing.

[0017] FIG. 3B shows a side section view of a self-separating bullet separating into sub-projectiles after firing.

[0018] FIG. 3C shows a side section view of sub-projectiles exiting a firearm muzzle after firing.

[0019] FIG. 4A shows a side section view of a self-separating bullet embodiment with single point V-notch grooves, a solid core, a tapered ogive, a leading segment cavity, and a first trailing segment with external flutes.

[0020] FIG. 4B shows an isometric view of a self-separating bullet embodiment with single point V-notch grooves, a solid core, a tapered ogive, a leading segment cavity, and a first trailing segment with external flutes.

[0021] FIG. 5A shows a side section view of a self-separating bullet embodiment with a single point V-notch groove, a solid core, a tapered ogive, a leading segment cavity, and a trailing segment cavity.

[0022] FIG. 5B shows an isometric view of a self-separating bullet embodiment with a single point V-notch groove, a solid core, a tapered ogive, a leading segment cavity, and a trailing segment cavity.

[0023] FIG. 6A shows a side section view of a self-separating bullet embodiment with a single point V-notch groove, a solid core, a needle nose leading segment, and a first trailing segment with external flutes.

[0024] FIG. 6B shows an isometric view of a self-separating bullet embodiment with a single point V-notch groove, a solid core, a needle nose leading segment, and a first trailing segment with external flutes.

[0025] FIG. 7A shows a side section view of a self-separating bullet embodiment with a single point V-notch groove, a solid core, a needle nose leading segment, and a trailing segment with a cavity and external flutes.

[0026] FIG. 7B shows an isometric view of a self-separating bullet embodiment with a single point V-notch groove, a solid core, a needle nose leading segment, and a trailing segment with a cavity and external flutes.

[0027] FIG. 8 shows a side section view of a self-separating projectile embodiment with external features / grooves comprising spacers / retaining rings / e-clips.

[0028] FIG. 9 shows a side section view of a self-separating projectile embodiment with a solid core and traditional groove geometries.

[0029] FIG. 10 shows a side section view of a self-separating projectile embodiment with a wadcutter profile trailing segment and a semi-wadcutter profile leading segment.

[0030] FIG. 11 shows a side section view a self-separating projectile embodiment with a Spitzer profile leading segment.DETAILED DESCRIPTION OF THE DRAWINGS

[0031] The embodiments of the invention described herein are not intended to be exhaustive or to limit the invention to precise forms disclosed. Rather, the embodiments selected for description have been chosen to enable one skilled in the art to practice the invention.

[0032] For purposes of this description, the terms “projectile” and “bullet” will be used interchangeably for a component of firearm ammunition that is fired from a firearm barrel.

[0033] Generally, provided is a projectile for a firearm comprising: a leading segment; one or more trailing segments; and a structurally weakened zone connecting each of the leading segment and the one or more trailing segments; wherein the structurally weakened zone enables separation of the segments as the projectile is fired and travels through a firearm barrel bore.

[0034] In an illustrative embodiment, the structurally weakened zone further comprises an external feature and an interior feature. In an illustrative embodiment, the external feature further comprises one or more grooves comprising a locally reduced cross-sectional area. In an illustrative embodiment, the external feature further comprises one or more sharp interior corner stress concentrators. In an illustrative embodiment, the interior feature further comprises an aperture or bore cavity. In an illustrative embodiment, the structurally weakened zone further comprises one or more single point V-notch grooves. In an illustrative embodiment, the single point V-notch grooves further comprise a locally reduced cross-sectional area. In an illustrative embodiment, the leading segment further comprises a solid core, a tapered ogive, and a cavity; wherein the cavity reduces the leading segment mass and shifts the leading segment center of gravity rearward and behind center of pressure to optimize spin stabilization after separation. In an illustrative embodiment, the trailing segment further comprises one or more external flutes to allow high pressure and high temperature gas to directly impinge upon the structurally weakened after firing. In an illustrative embodiment, the projectile further comprises a single point V-notch groove, a solid core, a tapered ogive, a leading segment cavity, and a trailing segment cavity. In an illustrative embodiment, the trailing segment cavity further comprises a tracer compound. In an illustrative embodiment, the projectile further comprises a single point V-notch groove, a solid core, a needle nose leading segment, and a first trailing segment comprising external flutes. In an illustrative embodiment, the needle nose leading segment permits a closer segment weight-match to the first and second trailing segments to accommodate comparable projectile seating depth and cartridge overall length to a conventional ball cartridge of a same caliber. In an illustrative embodiment, the projectile further comprises a single point V-notch groove, a solid core, a needle nose leading segment, and a trailing segment with a cavity and external flutes. In an illustrative embodiment, the trailing segment cavity further comprises a tracer compound. In an illustrative embodiment, the projectile further comprises one or more spacers / retaining rings / e-clips positioned in the structurally weakened zone. In an illustrative embodiment, the projectile further comprises a solid core and traditional groove geometries comprising one or more sharp interior corner stress concentrators per groove. In an illustrative embodiment, the projectile further comprises a Spitzer profile leading segment. In an illustrative embodiment, the projectile further comprises a semi-wadcutter leading segment profile and / or a wadcutter trailing segment profile.

[0035] In an illustrative embodiment, provided is a projectile for a firearm comprising: a leading segment; one or more trailing segments; and a structurally weakened zone connecting each of the leading segment and the one or more trailing segments; wherein the structurally weakened zone establishes diminished cross-sectional area for designed failure when acted upon by induced stress states, thermal effects, and associated reduction in material strength, or a combination thereof, leading to separation of the segments as the projectile is fired and travels through a firearm barrel bore.

[0036] In an illustrative embodiment, the structurally weakened zone further comprises an external feature and an interior feature. In an illustrative embodiment, the external feature further comprises one or more grooves. In an illustrative embodiment, the external feature further comprises one or more sharp interior corner stress concentrators. In an illustrative embodiment, the interior feature further comprises an aperture or bore cavity. In an illustrative embodiment, the structurally weakened zone further comprises one or more single point V-notch grooves. In an illustrative embodiment, the single point V-notch grooves further comprise a locally reduced cross-sectional area. In an illustrative embodiment, the leading segment further comprises a solid core, a tapered ogive, and a cavity; wherein the cavity reduces the leading segment mass and shifts the leading segment center of gravity rearward and behind center of pressure to optimize spin stabilization after separation. In an illustrative embodiment, the trailing segment further comprises one or more external flutes to allow high pressure and high temperature gas to directly impinge upon the structurally weakened zone after firing. In an illustrative embodiment, the projectile further comprises a single point V-notch groove, a solid core, a tapered ogive, a leading segment cavity, and a trailing segment cavity. In an illustrative embodiment, the trailing segment cavity further comprises a tracer compound. In an illustrative embodiment, the projectile further comprises a single point V-notch groove, a solid core, a needle nose leading segment, and a first trailing segment comprising external flutes. In an illustrative embodiment, the needle nose leading segment permits a closer segment weight-match to the first and second trailing segments to accommodate comparable projectile seating depth and cartridge overall length to a conventional ball cartridge of a same caliber. In an illustrative embodiment, the projectile further comprises a single point V-notch groove, a solid core, a needle nose leading segment, and a trailing segment with a cavity and external flutes. In an illustrative embodiment, the trailing segment cavity further comprises a tracer compound. In an illustrative embodiment, the projectile further comprises one or more spacers / retaining rings / e-clips positioned in the structurally weakened zone. In an illustrative embodiment, the projectile further comprises a solid core and traditional groove geometries comprising one or more sharp interior corner stress concentrators per groove. In an illustrative embodiment, the projectile further comprises a Spitzer profile leading segment. In an illustrative embodiment, the projectile further comprises a semi-wadcutter leading segment profile and / or a wadcutter trailing segment profile.

[0037] FIG. 1 shows a side section view of a self-separating bullet 101. In an illustrative embodiment, the device comprises a leading segment 102, one or more (in this embodiment, two) trailing segments 103, 104, and a structurally weakened zone 105 connecting each leading segment 102 and one or more trailing segments 103, 104. In an illustrative embodiment, the leading segment 102 comprises a necked section 109 to influence mass, center-of-gravity, and center-of-pressure, which helps to ensure stable flight after separation and upon muzzle exit.

[0038] In an illustrative embodiment, the structurally weakened zone 105 further comprises an external feature and an interior feature to enable separation of the segments 102, 103, 104 as the bullet 101 is fired and travels through a firearm barrel bore. In an illustrative embodiment, the external feature comprises one or more grooves 106 comprising a locally reduced cross-sectional area and one or more interior sharp corners 107. The grooves 106 serve to reduce the cross-sectional area, which yields higher stress for a given applied force to help enable separation. The interior sharp corners 107 serve as geometric stress concentrators, further increasing the stress applied in the reduced cross-sectional area created by the grooves 106.

[0039] In an illustrative embodiment, the interior feature comprises an aperture or bore cavity 108, which works in combination with the grooves 106 to further reduce the local cross-sectional area in the structurally weakened zone 105. Additionally, the bore cavity 108 offers a direct path for burning and expanding propellant gases to apply outward force, which generates additional axial and radial stress contributors. These stress contributors, along with a torsional shear stress developed in the reduced cross-sectional area of the structurally weakened zone 105 as the leading segment 102 of the self-separating bullet 101 initially engages with the origin or barrel rifling, produce a combined stress state of even greater magnitude. This combined stress state is then exaggerated by the presence of the sharp corners 107 and associated geometric stress concentration.

[0040] Given the associatively small thermal mass of the reduced cross-sectional area of the structurally weakened zone 105, direct access for heat transfer to occur via the bore cavity 108 and the use of common bullet materials of high thermal conductivity (such as copper), the presence of a bore cavity 108 can also be beneficially applied to rapidly increase the temperature of the material in the reduced cross-sectional area of the structurally weakened zone 105. As can be appreciated, the temperature increase leads to a reduction in material strength due to the inverse relationship between material strength and temperature for common metals and metal alloys used for bullet manufacture. Therefore, a deliberate application of stress contributors, stress concentration, and heat (to reduce material strength) are used in combination to enable conditions within the structurally weakened zone that exceed the structural capacity of the reduced cross-sectional area material of the structurally weakened zone 105. As a result, the self-separating bullet decomposes (breaks apart) through the act of firing into discrete sub-projectiles.

[0041] FIG. 2 shows a side section view of a self-separating bullet 101 as assembled in a cartridge case 201. The inventive bullet 101 can be utilized with conventional cartridge components (i.e., cartridge case, primer, and propellant) when assembling the cartridge. In some embodiments, the bullet 101 can be weight-matched and assembled with a seating depth equivalent to a bullet used in a conventional ball cartridge of the same caliber. As can be appreciated, weight-matching and comparable seating depth allows for assembly of the inventive bullet 101 within a cartridge case 201 utilizing not only the same propellant but also an equivalent propellant charge weight, which enables an equivalent launch velocity of the self-separating bullet 101 to the bullet used in the conventional ball cartridge of the same caliber. Furthermore, a weight-matched payload of the inventive bullet 101, relative to a bullet of a conventional ball cartridge in the same caliber, can also be accomplished without the need to increase overall cartridge length (which can lead to functional issues involving cartridge feeding and chambering, for example) or a deeper seating depth into the cartridge case 201 (which often requires a decrease in propellant charge weight and thereby a reduction in launch velocity, kinetic energy, and effective range).

[0042] FIG. 3A shows a side section view of a self-separating bullet 101 and a cartridge case 201 chambered in a firearm barrel and prior to firing, FIG. 3B shows a side section view of separation of a self-separating bullet into sub-projectiles 306-308 after firing, and FIG. 3C shows a side section view of sub-projectiles 306-308 exiting a firearm muzzle 302 after firing. In an illustrative embodiment, the firing sequence beings with ignition of the primer (not shown), which ignites the propellant charge (not shown) within the cartridge case 201. Ignition of the propellant charge causes compressive stress to act on the base 304 of the bullet 101, the base of the middle (first trailing) segment, as well as on the leading segment via front end of the bore cavity 108, all of which cause the bullet 101 to travel down the barrel bore 301.

[0043] The leading segment 102 engages the origin of rifling 305 and begins to rotate in a conventional manner. For the leading segment 102 to rotate during this time, it must associatively rotate the remaining rearward mass of the bullet 101 (in this embodiment the trailing segments 103, 104, which are not yet directly engaged with the rifling 305). The force required to rotate the trailing segments 103, 104 results in a torsional / shear stress in the structurally weakened zones 105 of the bullet 101. In addition, the burning propellant creates gas pressure that causes hoop / circumferential and longitudinal / axial stress to act on the bore cavity 108. Furthermore, the one or more interior sharp corners 107 additionally serves to induce geometric stress concentration, which further inflates the effective stress experienced in the structurally weakened zones 105. The combined stresses help ensure reliable material failure, bullet decomposition, and bullet separation into sub-projectiles 306-308 (as best shown in FIG. 3B), which occurs at the structurally weakened zones 105 since they experience the highest combined stresses as a function of reduced cross-sectional area and the presence of stress concentrators.

[0044] In addition to the stresses and stress concentrators, thermal effects further ensure bullet 101 separation into sub-projectiles 306-308. Specifically, the bore cavity 108 provides a direct gas path for the burning propellant to impinge on the interior surfaces of the connective structure in the structurally weakened zones 105. As can be appreciated, the extremely high temperature gas, minimal sectional area / thermal mass in the structurally weakened zones 105, and commonly used bullet materials of high thermal conductivity (such as copper) cause the temperature in this area to both rapidly and significantly increase via the ensuing heat transfer. As the material temperature of the bullet increases, its strength decreases, helping to ensure reliable projectile separation by effectively reducing the structural capability of the cross-sectional area in the structurally weakened zones 105. Furthermore, friction between the outer surfaces of the bullet 101 and the rifling 305 also lead to heat transfer and a rise in bullet 101 temperature, which can further serve to help reduce material strength.

[0045] As material failure occurs at the structurally weakened zones 105 and the bullet 101 separates, the individual sub-projectiles 306-308 continue engaging with the rifling 305 as they travel down the barrel bore 301. After bullet 101 separation and in addition to acting on the base 304 of the second trailing segment, the pressure created by the burning and expanding propellant acts on the base 304 of the leading 306 and first trailing sub-projectile 307, causing some physical separation therebetween in the axial direction while the sub-projectiles are in the barrel bore 301. Each sub-projectiles 306-308 continues engaging with the rifling 305 while traveling down the barrel bore 301, which imparts spin-stabilization upon exit from the muzzle 302 after firing. As can be appreciated, spin stabilization plays a role in the desired sub-projectile dispersion performance and ultimately extending effective range.

[0046] FIGS. 4A-B show views of a self-separating bullet 401 embodiment with single point V-notch grooves 402, a solid core 403, a tapered ogive 404, a leading segment cavity 405, and a first trailing segment 408 with external flutes 407. In an illustrative embodiment, the self-separating bullet 401 comprises a leading segment 406, one or more (in this embodiment, two) trailing segments 408, 409, and a structurally weakened zone 410 connecting the leading segment 406 and the one or more trailing segments 408, 409. In an illustrative embodiment, the structurally weakened zone 410 connecting the leading segment 406 and one or more trailing segments 408, 409 comprises single point V-notch grooves 402. This embodiment utilizes an external feature (V-notch grooves 402) without any internal feature. In an illustrative embodiment, V-notch grooves 402 lead to a reduced cross-sectional area of the structurally weakened zone 410. Additionally, the V-notch grooves 402 further comprise a sharp interior corner stress concentrator 411 at the root of the groove. The grooves 402 enable stress concentration in each structurally weakened zone 410 along with improved aerodynamic flight properties (a tapered forward section to reduce drag) for each trailing segment 408, 409.

[0047] In an illustrative embodiment, the leading segment 406 comprises a solid core 403, a tapered ogive 404, and a cavity 405 in leading segment 406. The cavity 405 in the forward segment (in this embodiment, a blind hole) reduces the mass of the leading segment 406 and shifts the center of gravity to the rear of the leading segment 406 (and behind the leading segment 406 center of pressure) to optimize spin stabilization after segment separation. Additionally, the cavity 405 provides a better individual segment weight-match to the individual weight of each trailing segment after separation.

[0048] In an illustrative embodiment, the external flutes 407 in one or more of the trailing segments (in this embodiment, in the first trailing segment 408) allow high pressure and high temperature gas from the burning propellant to reach and maximize contact with the single point V-notch grooves 402 in each structurally weakened zone during initial movement of the bullet 401 after firing. The high pressure and high temperature gas contacting the single point V-notch grooves 402 provides additional stress contributors and weakened material properties, which helps ensure reliable segment separation upon firing.

[0049] FIGS. 5A-B show views of a self-separating bullet 501 embodiment with a single point V-notch groove 502, a solid core 503, a tapered ogive 504, a leading segment cavity 505, and a trailing segment cavity 507. In an illustrative embodiment, the leading segment 506 comprises a cavity 505, which reduces the mass of the leading segment 506 and shifts the center of gravity to the rear of the leading segment 506 and behind the center of pressure to optimize spin stabilization after segment separation. Additionally, the cavity 507 in the trailing segment 508 allows for optional tracer 509 compounds and a closure cup (elements not shown). In an illustrative embodiment, the compound is a conventional tracer compound 509 formulation that is known in the art and is used in conventional tracer ammunition. The tracer compound 509 provides a shooter with immediate visual feedback on sub-projectile trajectories and an opportunity to adjust point-of-aim, if needed, to “walk the rounds” onto the intended target.

[0050] FIGS. 6A-B show views of a self-separating bullet 601 embodiment with a single point V-notch groove 602, a solid core 603, a needle nose leading segment 604, and a first trailing segment 606 with external flutes 605. In an illustrative embodiment, the needle nose leading segment 604 permits a closer segment weight-match to the first and second trailing segments 606, 607, while accommodating comparable bullet seating depth and cartridge overall length to the bullet used in a conventional ball cartridge of the same caliber. The needle nose leading segment 604 also allows the center of gravity of the leading segment 604 to be established behind the center of pressure, thereby aiding in spin stabilization upon muzzle exit.

[0051] FIGS. 7A-B show views of a self-separating bullet embodiment 701 with a single point V-notch groove 702, a solid core 703, a needle nose leading segment 704, and a trailing segment 706 with a cavity 705 and external flutes 707. In this embodiment, the bullet 701 comprises a needle nose leading segment 704 (for advantages described above) and a trailing segment 706 comprising a cavity 705 (for placement of optional tracer compound as described above) and external flutes 707 (for additional stress contributors and heat transfer to ensure reliable segment separation upon firing as described above).

[0052] FIG. 8 shows a side section view of a self-separating bullet 801 embodiment with external features / grooves comprising spacers / retaining rings / e-clips 802. Any of the embodiments described herein can utilize one or more spacers / retaining rings / e-clips 802 positioned in the external features / grooves. The spacers 802 can be used to positively maintain axial alignment of the projectile sections 804-806 during bullet seating and cartridge assembly and / or initial stages of projectile movement, once the cartridge is fired, as the sections initially engage the rifling.

[0053] FIG. 9 shows a side section view of a self-separating projectile 901 embodiment with a solid core 902 and traditional groove geometries 903. In an illustrative embodiment, the self-separating projectile 901 can implement more traditional groove geometries 903 (with two sharp interior corner stress concentrators per groove) as compared with the single point V-notch style grooves as shown in other embodiments. In an illustrative embodiment, the solid core 902 and traditional groove geometries 903 embodiment can further include spacers / e-clips as shown above.

[0054] FIG. 10 shows a side section view of a self-separating bullet 1001 embodiment with a wadcutter profile trailing segment 1002 and a semi-wadcutter profile leading segment 1003. In an illustrative embodiment, the inventive self-separating projectile 1001 can be adapted for use in pistol-calibers (including but not limited to 9×19 mm, 0.45 ACP, 0.357 S&W Magnum, etc.) with the addition of one or more grooves 1004 that lead to self-separation of the initial semi-wadcutter bullet type into sub-projectiles with a leading sub-projectile 1003 maintaining a semi-wadcutter profile and one or more trailing sub-projectile 1002 assuming a wadcutter profile.

[0055] FIG. 11 shows a side section view a self-separating projectile 1101 embodiment with a Spitzer profile 1102 leading segment 1103. In an illustrative embodiment, conventional full-metal jacket (ball) ammunition comprising a Spitzer profile 1102 can be modified with one or more grooves 1104 (a single point V-notch or a more traditional groove geometry) that leads to self-separation of the leading segment 1103 and one or more trailing segments 1105.

[0056] Overall, the inventive self-separating bullet overcomes the known deficiencies of multiplex rounds as well as those “pelletized” ammunition types utilizing spherical sub-projectiles. The self-separating bullet can be used for military applications, primarily for Counter-UAS, and for commercial applications, such as for home and personal defense. The inventive self-separating bullet provides improved projectile-multiplying kinetic effects when firing ammunition through existing small arms (i.e. long guns other than shotguns) for counter-UAS compared to historical multiplex rounds. The inventive self-separating bullet produces shotgun-style effects that carry an effective range far greater than the capabilities of conventional shotguns, even those firing buckshot-sized payload of high-density materials such as tungsten. While greater than conventional shotgun rounds, the self-separating bullet advantageously provides a reduced effective range and associated collateral damage concerns as compared to firing traditional ammunition of a “ball round” or similar type.

[0057] Additionally, the axial separation leads to more useful dispersion and disbursed kinetic effects on target. Since the sub-projectiles of the self-separating bullet remain directly engaged with the barrel rifling after separation and can be designed to maintain spin stabilization at muzzle exit, the self-separating bullet produces kinetic effects that dramatically improve effective range over competing projectile-multiplying designs such as those offering several sub-caliber spherical projectiles. Furthermore, the self-separating bullet can be fired through suppressed firearms (i.e. firearms equipped with sound suppressors whereby the exiting sub-projectile must additionally travel through the bore of a secondary device after muzzle exit from the barrel).

[0058] Finally, the inventive bullet is far more cost-effective to produce compared with competing designs, such as those offering several sub-caliber spherical projectiles or others offering stacked individual projectiles.

[0059] Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the spirit and scope of the invention as described and defined in the following claims.

Claims

1. A projectile for a firearm comprising:a leading segment;one or more trailing segments; anda structurally weakened zone connecting each of said leading segment and said one or more trailing segments;wherein said structurally weakened zone enables separation of said segments as said projectile is fired and travels through a firearm barrel bore.

2. The projectile of claim 1, wherein said structurally weakened zone further comprises an external feature and an interior feature.

3. The projectile of claim 2, wherein said external feature further comprises one or more grooves comprising a locally reduced cross-sectional area.

4. The projectile of claim 2, wherein said external feature further comprises one or more sharp interior corner stress concentrators.

5. The projectile of claim 2, wherein said interior feature further comprises an aperture or bore cavity.

6. The projectile of claim 1, wherein said structurally weakened zone further comprises one or more single point V-notch grooves.

7. The projectile of claim 6, wherein said single point V-notch grooves further comprise a locally reduced cross-sectional area.

8. The projectile of claim 1, wherein said leading segment further comprises a solid core, a tapered ogive, and a cavity;wherein said cavity reduces said leading segment mass and shifts said leading segment center of gravity rearward and behind center of pressure to optimize spin stabilization after separation.

9. The projectile of claim 1, wherein said trailing segment further comprises one or more external flutes to allow high pressure and high temperature gas to directly impinge upon said structurally weakened after firing.

10. The projectile of claim 1, wherein said projectile further comprises a single point V-notch groove, a solid core, a tapered ogive, a leading segment cavity, and a trailing segment cavity.

11. The projectile of claim 10, wherein said trailing segment cavity further comprises a tracer compound.

12. The projectile of claim 1, wherein said projectile further comprises a single point V-notch groove, a solid core, a needle nose leading segment, and a first trailing segment comprising external flutes.

13. The projectile of claim 12, wherein said needle nose leading segment permits a closer segment weight-match to said first and second trailing segments to accommodate comparable projectile seating depth and cartridge overall length to a conventional ball cartridge of a same caliber.

14. The projectile of claim 1, wherein said projectile further comprises a single point V-notch groove, a solid core, a needle nose leading segment, and a trailing segment with a cavity and external flutes.

15. The projectile of claim 14, wherein said trailing segment cavity further comprises a tracer compound.

16. The projectile of claim 1, wherein said projectile further comprises one or more spacers / retaining rings / e-clips positioned in said structurally weakened zone.

17. The projectile of claim 1, wherein said projectile further comprises a solid core and traditional groove geometries comprising one or more sharp interior corner stress concentrators per groove.

18. The projectile of claim 1, wherein said projectile further comprises a Spitzer profile leading segment.

19. The projectile of claim 1, wherein said projectile further comprises a semi-wadcutter leading segment profile and / or a wadcutter trailing segment profile.

20. A projectile for a firearm comprising:a leading segment;one or more trailing segments; anda structurally weakened zone connecting each of said leading segment and said one or more trailing segments;wherein said structurally weakened zone establishes diminished cross-sectional area for designed failure when acted upon by induced stress states, thermal effects, and associated reduction in material strength, or a combination thereof, leading to separation of said segments as said projectile is fired and travels through a firearm barrel bore.

21. The projectile of claim 20, wherein said structurally weakened zone further comprises an external feature and an interior feature.

22. The projectile of claim 21, wherein said external feature further comprises one or more grooves.

23. The projectile of claim 21, wherein said external feature further comprises one or more sharp interior corner stress concentrators.

24. The projectile of claim 21, wherein said interior feature further comprises an aperture or bore cavity.

25. The projectile of claim 20, wherein said structurally weakened zone further comprises one or more single point V-notch grooves.

26. The projectile of claim 25, wherein said single point V-notch grooves further comprise a locally reduced cross-sectional area.

27. The projectile of claim 20, wherein said leading segment further comprises a solid core, a tapered ogive, and a cavity;wherein said cavity reduces said leading segment mass and shifts said leading segment center of gravity rearward and behind center of pressure to optimize spin stabilization after separation.

28. The projectile of claim 20, wherein said trailing segment further comprises one or more external flutes to allow high pressure and high temperature gas to directly impinge upon said structurally weakened zone after firing.

29. The projectile of claim 20, wherein said projectile further comprises a single point V-notch groove, a solid core, a tapered ogive, a leading segment cavity, and a trailing segment cavity.

30. The projectile of claim 29, wherein said trailing segment cavity further comprises a tracer compound.

31. The projectile of claim 20, wherein said projectile further comprises a single point V-notch groove, a solid core, a needle nose leading segment, and a first trailing segment comprising external flutes.

32. The projectile of claim 31, wherein said needle nose leading segment permits a closer segment weight-match to said first and second trailing segments to accommodate comparable projectile seating depth and cartridge overall length to a conventional ball cartridge of a same caliber.

33. The projectile of claim 20, wherein said projectile further comprises a single point V-notch groove, a solid core, a needle nose leading segment, and a trailing segment with a cavity and external flutes.

34. The projectile of claim 33, wherein said trailing segment cavity further comprises a tracer compound.

35. The projectile of claim 20, wherein said projectile further comprises one or more spacers / retaining rings / e-clips positioned in said structurally weakened zone.

36. The projectile of claim 20, wherein said projectile further comprises a solid core and traditional groove geometries comprising one or more sharp interior corner stress concentrators per groove.

37. The projectile of claim 20, wherein said projectile further comprises a Spitzer profile leading segment.

38. The projectile of claim 20, wherein said projectile further comprises a semi-wadcutter leading segment profile and / or a wadcutter trailing segment profile.

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