Delivery of Projectiles from a Rifled Bore

This patent application is a bypass continuation of PCT/US2025/015970, filed Feb. 14, 2025, titled DELIVERY OF PROJECTILES FROM A RIFLED BORE, which claims the benefit of U.S. Provisional Application No. 63/554,042, titled DELIVERY OF PROJECTILES FROM A RIFLED BORE, filed Feb. 15, 2024, the contents of which are expressly incorporated by reference herein.

The present invention is directed to cartridges for precision grenadier systems having projectiles with a selected fragment size, velocity, pattern distribution, and other predetermined characteristics.

Advancements in ammunition for precision grenadier systems have improved the capabilities and reliability of these weapons to engage defiladed positions, unmanned aerial systems, light armored vehicles, and door breaches. For example, improvements in propellant technology have led to the development of higher-velocity rounds, enhancing both range and accuracy. Additionally, improvements in projectile design, such as aerodynamic shaping and advanced materials, have increased terminal ballistics and penetration capabilities against a variety of targets. Overall, these advancements in precision grenadier systems ammunition technology have significantly enhanced the lethality and versatility of precision grenadier systems in modern combat scenarios.

Precision grenadier systems are configured to deliver a payload to a target at a range up to about 1,000 meters using about 30,000 pounds per square inch (psi) of propellant pressure, with a relatively short rifled barrel (e.g., less than 18-inch barrel or less than 34 inches overall length) which may include titanium or its alloys. Generally, precisions grenadier systems must include robust platforms suitable for passing drop tests, water or debris intrusion, radiation exposure, or the like while maintaining operational capabilities. Although precisions grenadier systems have improved capabilities and reliability in some applications, there remains a need to enable or improve engagement of close combat targets. Close combat target rounds are capable of delivering lethal effects to exposed personnel targets within a range of less than about 75 meters.

The present disclosure describes ammunition cartridges for precision grenadier systems and other medium caliber armaments, including portable, semi-automatic, magazine-fed integrated armament systems. The disclosed ammunition cartridges are configured to deliver to a target at a range of at least 35 meters, such as at least 75 meters, projectiles having a selected size, velocity, and pattern distribution. In this way, the present disclosure provides for ammunition cartridges suitable for engagement of close combat targets.

The ammunition cartridges described herein are distinct from ammunition for shotguns at least in that the described ammunition cartridges include robust payloads for discharge at pressures exceeding 30,000 psi, suitable for use in rifled barrels, a dome distal end to facilitate reliable loading for semi-automatic operation, having a caliber equal to or greater than about 20 mm, and the like. Conversely, shotgun ammunition is generally configured for operation in smooth bore barrels at pressures less than 20,000 psi, having a planar distal end, and a caliber less than 20 mm.

In some examples, the disclosure describes an ammunition cartridge centered about a longitudinal axis and extending from a proximal end to a distal end. The cartridge includes a case, a propellant, a body, a cap, and one or more projectiles. The case includes a base defining the proximal end of the cartridge and a case sidewall extending from the base to a distal mouth and defining a case cavity. The propellant charge is disposed in at least a portion of the case cavity and configured to deliver the projectiles to a target. The body includes a proximal cup and a body sidewall extending to a distal interface. At least a proximal portion of the body is receivable in the case cavity distal to the propellant charge. The cap extends from a proximal cap portion coupled to the distal interface of the body to a dome defining the distal end of the cartridge. The body and the cap define a projectile cavity. The one or more projectiles are positioned within the projectile cavity.

In some examples, the case is a steel case having a diameter of 25 millimeters and the base houses at least one of a percussion primer, a booster pellet, and a flash tube. This enables the cartridge to be fired from a precision grenadier system. Additionally, or alternatively, at least a portion of the base may define an extractor ring configured to provide for semi-automatic operation of a firearm and feed from a magazine.

In some examples, the propellant charge is configured to propel the at least the one or more projectiles from a firearm with a muzzle velocity within a range from about 700 fect per second (ft/s) (213 meters per second (m/s)) to about 1,600 ft/s (488 m/s). In other examples, the muzzle velocity may be less than about 1,116 ft/s, thereby providing for a subsonic projectile which may reduce or prevent determination of shooter position based on acoustic characteristics of the one or more projectiles.

In some examples, the cartridge includes at least one of an obturating ring and a driving band. The obturating ring and/or the driving band may be integrally formed with the body sidewall, directly coupled to the body sidewall, or rotatable coupled to the body sidewall. The obturating ring and/or driving band may be disposed adjacent to an exterior surface of the body sidewall to provide for sealing of propellent gases, engagement of barrel rifling, or both. The obturating ring and/or the driving band may be rotatably coupled to the body sidewall such that, when discharged from a firearm, the is obturating ring and/or the driving band may at least partially engage a rifling of the firearm but may not fully transmit rotation to the body thereby decoupling a spin rate of the body relative to the rifling. In this way, the spin rate of the body when discharged from the barrel may be controlled.

In some examples, the obturating ring and/or the driving band is disposed radially adjacent at least a first portion of the cap such that, when discharged from a firearm, the obturating ring and/or the driving band may engage a rifling of a barrel of the firearm and translate a compressive force to the first portion of the cap to fracture or displace at least a second portion of the cap. In this way, upon firing, the cartridge may be configured to reliably fracture a select portion of the cap to provide for predicable separation of the cap and one or more projectiles as well as patterning of the one or more projectiles.

Additionally, or alternatively, the cartridge may include a sleeve defining a cylindrical annulus extending from a proximal sleeve portion radially adjacent to the proximal cup of the body to a distal sleeve portion engaged with the proximal cap portion. Optionally, the sleeve may define or be coupled with an obturating ring and/or a driving band. When discharged from a firearm, in response to an axial force on the body, the sleeve may be configured to translate axial in the proximal direction relative to the cap to disengage from the proximal cap portion. In this way, upon firing, the cartridge may be configured to reliably provide for predicable separation of the cap and one or more projectiles as well as patterning of the one or more projectiles.

In some examples, the proximal cup defines a distal facing surface having a curvature shaped to receive therein at least one of the one or more projectiles. The curved surface may reduce or prevent movement of the one or more projectiles, for example, during discharge from a firearm, thereby providing for a more reliable patterning compared to a proximal cup with a planar distal facing surface.

In some examples, the proximal cup defines a proximal facing surface configured to, when discharged from a firearm, in response to a pressure produced by the propellant charge, splay in a radial direction to seal propellant gases distal of the body. Additionally, or alternatively, the proximal cup, e.g., the proximal facing surface, may include a proximally extending skirt configured to, when discharged from a firearm, splay in the radial direction. The skirt may extend from a plane normal to the longitudinal axis and extending through a proximal end of the projectile cavity to a proximal edge a length within a range from about 0.750 inches (1.91 centimeters (cm)) to about 0.800 inches (20.32 cm). The length of the skirt may be selected to provide engagement with rifled barrel of a firearm to cause a first spin of the body in a first circumferential direction.

In some examples, the cartridge may be configured to discharge from a firearm having a rifled barrel and a counter-rotating muzzle device. The rifled barrel may have any suitable twist rate, such as a 1×25″ twist rate. The counter-rotating muzzle device may have a similar twist rate (opposite that of the rifled barrel) or a gain twist. A bore of the counter-rotating muzzle may be greater than a bore of the rifled barrel such that the rifled barrel may impart on a first ammunition type a first spin rate and the combination of the rifled barrel and the counter-rotating muzzle device may impart on a second ammunition type a second spin rate that is less than the first spin rate. For example, when discharged from a firearm having a counter-rotating muzzle device, at least a portion of the described cartridges, such as a obturating ring, a driving band, a portion of the body, or a skirt of the body, may be configured to engage a counter-rotating muzzle device of a firearm to at least one of partially despin of the body or cause a second spin of the body in a second, opposing circumferential direction. In these ways, a counter-rotating muzzle device and engagement therewith by features of a cartridge may be used to control a spin rate.

In some examples, the body sidewall includes at least one of a plurality of skives, a plurality of slits, or other features that, when discharged from a firearm, and in response to an air-resistance on the body sidewall and/or a pressure produced by the propellant, urge at least a portion of the body sidewall radially outward. The portions of the body sidewall may project distally, proximally, or combinations thereof. The projecting portions of the body sidewall may provide a predicable distance of travel of the body with the projectiles before separation of the body from the projectiles.

In some examples, the proximal cup includes an aperture configured to, when discharged from a firearm, in response to a propellant gas produced by the propellant, pass therethrough a portion of the propellant gas. The aperture may include a valve configured to close in response to a threshold pressure. Also, the cartridge may include an elongate tube extending from a proximal end fluidly coupled to the aperture to a distal end disposed adjacent to the cap, such that the elongate tube is configured to, when discharged from a firearm, in response to a propellant gas produced by the propellant, pass therethrough a portion of the propellant gas to rupture or displace relative to the body at least a portion of the cap. By controllably venting a portion of the propellant gas into the projectile cavity, the cartridge may be configured to rupture, fracture, or otherwise displace at least a portion of the cap to facilitate predicable separation of the one or more projectiles from the body.

In some examples, the cap may include a frangible material configured to, when discharged from a firearm, fracture to expose the one or more projectiles. The frangible material defines at least part of the proximal cap portion to facilitate disengagement of the cap from the body. The frangible material of the cap may be configured to fracture in response to a force, such as a pressure produced from a propellant, friction of the payload with a barrel, air-resistance, centripetal force, or the like. Fracture of a frangible cap may be configured to facilitate separation of projectiles for a payload. In this way, materials may be selected to control or improve performance of the cartridge, such as patterning or range of projectiles.

In some examples, the cartridge may include one or more projectile retainers disposed within the projectile cavity and configured to retain the one or more projectiles in a selected special arrangement. The retainers may include a metal or polymeric cage or baffles defining at least one axial extending support and at least one radially extending support. Additionally, or alternatively, the retainers may include at least one circumferentially extending support. The retainers are configured to constrain the one or more projectiles in at least one of an axial direction, a circumferential direction, and a radial direction. In some examples, the retainers may resist centripetal forces when discharge from a firearm, thereby providing improved control of projectile pattern.

For purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the disclosure is intended by the illustration and description of certain embodiments of the disclosure. In addition, any alterations and/or modifications of the illustrated and/or described embodiment(s) are contemplated as being within the scope of the present disclosure. Further, any other applications of the principles of the disclosure, as illustrated and/or described herein, as would normally occur to one skilled in the art to which the disclosure pertains, are contemplated as being within the scope of the present disclosure.

is a conceptual diagram illustrating an example firearm system. Firearm systemincludes a stock, a receiver, optics, a rifled barrel, counter-rotating muzzle device, piston grip, trigger, magazine, and ammunition cartridge. In some examples, firearm systemmay include fewer components, additional components, or alternative components.

Firearm systemmay be configured to fire any suitable caliber of ammunition cartridge, such as, for example, small caliber cartridges having a caliber less than about 20 millimeters (mm) or medium caliber having a caliber within a range from about 20 mm to about 57 mm. In some examples, firearm systemmay include an autocannon, a grenade launcher, a precision grenadier system, or other medium caliber armament. Firearm systemmay be a portable system configured to single operator use in combat scenarios.

Stockis configured to enable an operator to brace and aim firearm system. For example, a single operator may be suitable to aim and discharge firearm system. Stockmay be removable or excluded, such that firearm systemmay be coupled to a second firearm or a mounting device.

Receivermay include components configured to facilitate operation, such as semi-automatic operation, of firearm system. Receivermay house action components such as, for example, a hammer, a bolt, a breechblock, a firing pin, an extractor, a safety, and the like.

Opticsincludes one or more devices suitable to aim firearm system. For example, optics may include one or more of iron sights, telescopic sights, holographic sights, laser sights, variable magnification, or the like. In some examples, opticsinclude optoelectronics which are configured to facilitate acquisition or engagement of a target, including, but not limited to, integrated rangefinder, wind sensor, acoustic sensor, ballistic support devices, augmented reality or digital overlay, or the like.

Rifled barrelis configured to receive therethrough a payload of cartridges. For example, rifled barreldefines a bore corresponding to a caliber of the payload of cartridge. Rifled barrelmay include any suitable rifling, such as, for example, a 1×25″ twist rate (e.g., pitch). In some examples, at least a portion of rifled barrelmay include a smooth bore, a gain twist, or other barrel features.

Counter-rotating muzzle deviceis configured to despin or counter spin the payload of cartridgebefore the payload exits firearm system. In some examples, counter-rotating muzzle devicemay define a bore having rifling that opposes the rifling of rifled barrel. In the case of a clockwise rifling of rifled barrel, counter-rotating muzzle devicemay include a counterclockwise rifling. The rifling of counter-rotating muzzle devicemay include any suitable rifling, such as, for example, a 1×25″ twist rate. In some examples, counter-rotating muzzle devicemay have a gain twist that starts at a low or zero twist rate with progressively greater twist rate until a final twist rate at the muzzle. The low or zero twist rate may reduce instantaneous spin direction change and/or possible stripping of portions of the payload.

In some examples, the bore diameter of counter-rotating muzzle devicemay be greater than a bore diameter of rifled barrel. The difference in diameter may enable a first ammunition type (e.g., for which a spin rate imparted by rifled barrelis desired) to be discharged from firearm systemwithout engagement of the counter-rotating muzzle device, and enable a second ammunition type (e.g., for which a spin rate imparted by rifled barrelis less desired) having as playable portion to engage the counter-rotating muzzle device. The first ammunition may include a high explosive fused round having a rigid outer surface. In some examples, the difference in bore diameter of the rifled barreland the counter-rotating muzzle devicemay be within a range from about 0.010 inches (0.254 mm) to about 0.050 inches (1.27 mm). The difference in bore diameter may be selected, in some examples, to limit a maximum yaw of a rigid round within the counter-rotating muzzle deviceto less than about 10 degrees, such as less than about 5-degress.

In some examples, counter-rotating muzzle devicemay define a muzzle brake configured to reduce recoil. In some examples, the muzzle brake defined by counter-rotating muzzle devicemay be configured to produce a selected flaring of at least a portion of the payload of cartridgeas it exists the muzzle, as discussed in further detail below.

Piston gripis configured to enable one-handed actuation of trigger. In some examples, piston gripand trigger(as well as features of receiver) may be configured for or reconfigurable to accommodate ambidextrous operation of firearm system.

Magazineis configured to protect and retain cartridges, as well as to facilitate semi-automatic operation of firearm system. Magazinemay be configured to retain any suitable number of cartridges, such as two cartridges, five cartridges, ten cartridges, or more. In some examples, magazinemay be configured to single hand removal or insertion.

Cartridgesmay include any suitable caliber and shape. Cartridgeincludes a domed distal end to facilitate translation of cartridgefrom magazineinto a chamber of receiverduring semi-automatic operation of firearm system. Cartridgealso includes an extractor ring to facilitate extraction of a spent cartridge after discharge of a payload. In some examples, cartridgemay include a plurality of projectiles for engagement of close combat targets, as discussed is further detail below.

are conceptual diagrams illustrating an example cartridge. Cartridgeis centered about a longitudinal axisand extends from a proximal endto a distal end. Cartridgeincludes a case, a propellant charge, and a payload. Payloadmay include a bodyand a capdefining a projectile cavityhousing one or more projectiles, and an optional sleeveand optional obturating ring or driving band. Cartridgemay include fewer features, additional features, or alternative features.

Caseincludes a basedefining proximal endand a case sidewallextending from baseto a distal mouthand defining a case cavity. Casemay include any suitable material. In some examples, casemay include steel, aluminum, brass, polymeric materials, thermoplastics, thermoset plastics, polycarbonate, polyamide, nylon, or the like. Polymeric materials may be preferred to reduce the weight of cartridge, with thermoplastics being more suitable for molding processes relative to thermoset plastics. Basedefines an aperture configured to receive a percussion primerthat may be operatively coupled to an ignition device, such as a booster pellet or a flash tube. At least a portion of the base defines an extractor ringconfigured to facilitate extraction of casefrom a chamber of a firearm system after discharge of payload.

In some examples, distal mouthof casemay be coextensive with at least a portion of payloador nearly or completely enclose payload. For example, distal mouthmay terminate along any portion of bodyor capor may extend a full length of cartridgeand at least partially encapsulated capat a hemispherical crimp. In some examples, by extending the full length of cartridge, casemay provide additional protection to payload prior to firing, facilitate semiautomatic feeding or chambering of cartridge, or both.

Casemay have a diameter of at least 20 mm, such as at least 25 mm or at least 30 mm. The diameter of casemay be selected to receive, within at least a portion of case cavity, a portion of payloadhaving a caliber equal to or greater than 20 mm, such as a 25 mm caliber, a 30 mm caliber, a 40 mm caliber, or a 50 mm caliber.

Propellant chargeis disposed in at least a portion of case cavity. In some examples, an amount of propellant chargemay be selected to control a muzzle exit energy of payload. For example, muzzle exit energy may be selected to be within a range from about 1800 foot-pounds to about 2000 foot-pounds, such as about 1939 foot-pounds. Muzzle exit energy may be correlated to, based on a mass of payload, a recoil force, a muzzle exit velocity of payload, or both. In some examples, a muzzle exit velocity may be selected within a range from about 550 feet per second (ft/s) (168 meters per second (m/s)) to about 1400 ft/s (427 m/s) For example, Table 1 illustrates example muzzle exit velocity of selected masses of payloadat a muzzle exit energy of about 1939 foot-pounds.

Bodyincludes a proximal cupand a body sidewallextending to a distal interface. At least a proximal portionof bodyis receivable in case cavitydistal to propellant charge. Proximal cupdefines a distal facing surface(also referred to as a shot cup) and a proximal facing surface(also referred to as a propellant cup).

Distal facing surfaceis configured to retain projectilesand may define a curvature shaped to receive therein at least one of projectiles. By receiving at least one of projectiles, distal facing surfacemay reduce movement of projectilesor deformation of proximal cupduring discharge, either or both of which may provide a more stabile trajectory of payload.

Proximal facing surfacemay be configured to, when discharged from a firearm, in response to a pressure produced by propellant charge, splay in a radial direction (as indicated by arrow R) to seal propellant gases proximal of body. This sealing of propellant gases may provide a greater muzzle exit energy per unit (e.g. mass or volume) of propellant chargecompared to a body that is not configured to radially splay. Additionally, or alternatively, the radially splayed portion of proximal facing surfacemay contact or otherwise interact with rifling of a barrel (e.g., rifled barrel), counter-rotation muzzle device (e.g., counter-rotating muzzle device), or both to cause a spin of payloadas it travels through the barrel and/or muzzle device.

In some examples, proximal cup(e.g., proximal facing surface) may include a proximally extending skirt. Skirtis optional. Skirtis configured to, when discharged from a firearm and/or in response to a pressure produced by the propellant charge, splay in the radial direction. Skirtextends from a plane normal to the longitudinal axis and extending through a proximal end of projectile cavityto a proximal edge a length within a range from about 0.750 inches (1.91 centimeters (cm)) to about 0.800 inches (20.32 cm).

In some examples, skirtmay include fins, pleats, folds, baffles, bellows, or other suitable features such as those described in U.S. Pat. Nos. 10,422,611; 9,879,957; 10,935,354; and D847,293; the entirety of each of which is incorporated by reference herein.

At least a portion of a splayed skirtmay contact or otherwise interact with rifling of a barrel (e.g., rifled barrel), counter-rotation muzzle device (e.g., counter-rotating muzzle device), or both to cause a spin of payloadas it travels through the barrel and/or muzzle device. In some examples, skirtmay be configured to engage a rifled barrel of a firearm to cause a first spin of the body in a first circumferential direction (e.g., a clockwise direction). Additionally, or alternatively, skirtmay be configured to engage a counter-rotating muzzle device of a firearm to at least one of partially despin payload(e.g., body, cap, or sleeve) or cause a second spin of payloadin a second, opposing circumferential direction (e.g., a counterclockwise direction). After exiting a muzzle of a firearm, splayed skirtmay provide an air-resistance to facilitate predicable separation of bodyfrom projectilesand, thereby, provide for a predicable patterning of projectiles.

Although described as including a proximal facing skirt, in other examples, at least a portion of bodymay define other features including distally facing hinged fins or flaps that, after exiting the muzzle, fully deploy to provide an air-resistance to facilitate predicable separation of bodyfrom projectilesand, thereby, to provide for a predicable patterning of projectiles. For example, body sidewallmay include at least one of a plurality of skives and a plurality of slits configured to, when discharged from a firearm, in response to at least one of an air-resistance, an inertia of projectileagainst proximal cup, and a pressure produced by propellant charge, urge at least a portion of body sidewallradially outward.

In some examples, proximal cupmay define at least one aperture configured to, when discharged from a firearm, in response to a propellant gas produced by propellant charge, pass therethrough a portion of the propellant gas from propellant cavityto projectile cavity. In this way, projectile cavitymay be at least partially pressurized during discharge to produce a desired effect on body, cap, or both, as discussed in further detail below.

In some examples, the aperture may include a valve configured to close in response to a threshold pressure. For example, the threshold pressure may be 10,000 pounds per square inch (psi), 20,000 psi, or 30,000 psi. The threshold pressure may be selected based on the desired effect on bodyor cap, such as a pressure required to fracture at least a portion of the cap.

In some examples, an elongate tube may be fluidly coupled to the aperture. The elongate tube may extend from a proximal end fluidly coupled to the aperture to a distal end disposed adjacent to cap. When discharged from a firearm, in response to a propellant gas produced by the propellant, the aperture and elongate tube may pass therethrough a portion of the propellant gas to rupture or displace relative to bodyat least a portion of cap.

Capextends from a proximal cap portioncoupled to distal interfaceof bodyto a domedefining distal endof cartridge. Proximal cap portionmay define one or more protrusions or recesses that are configured to releasably engage one or more corresponding recesses or protrusions defined by distal interface. In some examples, proximal cap portionmay release or disengagement from distal interfacein response to an inertia of a portion of payload, a pressurization of projectile cavity, a compression of payloadimparted by a firearm barrel, an air-resistance, or a centripetal force.

Domemay include any suitable shape. In some examples, a shape of domemay be selected to facilitate translation of cartridgefrom a magazine (e.g., magazine) into a chamber of a receiverof a firearm. Additionally, or alternatively, a shape of domemay be selected to provide a desired flight performance of payload. For example, domemay define a suitable ogive, such as a tangent ogive, a secant ogive, of a hybrid ogive.