TECHNICAL FIELD OF THE INVENTION

The present invention generally relates to ammunition articles, and more particularly to subsonic ammunition casings having a propellant insert formed from polymeric materials.

STATEMENT OF FEDERALLY FUNDED RESEARCH

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIALS FILED ON COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION

Without limiting the scope of the invention, its background is described in connection with lightweight polymer subsonic ammunition casing and more specifically to a lightweight polymer subsonic ammunition casing having a propellant insert positioned in the propellant chamber to reduce the internal volume of the propellant chamber.

Generally, there are two types of ammunition: supersonic ammunition, which fires projectiles with velocities exceeding the speed of sound; and subsonic ammunition, which fires projectiles with velocities less than that of the speed of sound and generally in the range of 1,000-1,100 feet per second (fps), most commonly given at 1,086 fps at standard atmospheric conditions. Traditional methods of making subsonic ammunition reduce the propellant charge (and in turn increasing the empty volume left vacant by the reduced propellant charge) in the shell until the velocity is adequately reduced.

Unfortunately, this empty volume can cause numerous problems including inhibition of proper propellant burn, inconsistent propellant positioning, reduced accuracy and propellant detonation caused by extremely high propellant burn rates. For example, since the propellant is free to move in the large empty volume, shooting downward with the propellant charge away from the primer gives different velocity results than when shooting upwards with the propellant charge close to the primer. Finally, usage of subsonic ammunition, and its attending lower combustion pressures, frequently results in the inability to efficiently cycle semi-automatic or fully automatic weapons where the propellant charge must produce sufficient gas pressure and/or volume to accelerate the projectile and to cycle the firing mechanism. With a reduced quantity of propellant, subsonic ammunition generally fails to produce sufficient pressure to properly cycle the firing mechanism. The art has provided numerous attempts to cure these problems, e.g., the introduction of inert fillers, expandable inner sleeves that occupy the empty space between the propellant and the projectile, insertion of flexible tubing, foamed inserts, stepped down stages in the discharge end of cartridge casings, or complicated three and more component cartridges with rupturable walls and other complicated features. Another approach has been to use standard cartridges in combination with non-standard propellants. However, the result of such prior attempts to solve the production of reliable subsonic cartridges have failed and let to subsonic rounds that have a larger variation in velocity and variance in accuracy potential.

In addition the use of polymer ammunition results in additional drawbacks, e.g., the possibility of the projectile being pushed into the cartridge casing, the bullet pull being too light such that the bullet can fall out, the bullet pull being too insufficient to create sufficient chamber pressure, the bullet pull not being uniform from round to round, and portions of the cartridge casing breaking off upon firing causing the weapon to jam or damage or danger when subsequent rounds are fired or when the casing portions themselves become projectiles. Accordingly, a need exists to develop solutions that make it possible to manufacture better and more price competitive subsonic ammunition than previously available.

SUMMARY OF THE INVENTION

The present invention provides a subsonic ammunition including a polymeric casing body comprising a generally cylindrical hollow polymer body having a body base at a first end thereof and a mouth at a second end to define a propellant chamber; a propellant insert positioned in the propellant chamber to reduce the internal volume of the propellant chamber, wherein the propellant chamber has an internal volume that is between 25 and 80% less than the open internal volume of a standard casing of equivalent caliber; a propellant disposed and confined within the propellant chamber; a primer insert positioned at the body base and in communication with the propellant chamber; a primer disposed in the primer insert in combustible communication with the propellant; and a projectile frictionally fitted in the mouth in combustible communication with the propellant. The projectile does not exceed the velocity of 1,200 feet per second at sea level under standard atmospheric conditions when fired. The projectile may be secured to the mouth by a mechanical interference, adhesive, ultrasonic welding, the combination of molding in place and adhesive, and hot crimping after the act of molding. The polymer body may include a material selected from the group consisting of polyphenylsulfone, polycarbonate, and polyamide. The subsonic ammunition may further include at least one additive selected from the group consisting of plasticizers, lubricants, molding agents, fillers, thermo-oxidative stabilizers, flame-retardants, coloring agents, compatibilizers, impact modifiers, release agents, reinforcing fibers and reinforcing agents. The propellant insert may have a substantially cylindrical shape, a free formed shape, a one or more ribs extending into the propellant chamber or a radial cross-section selected from the group consisting of circular, ovoid, octagonal, hexagonal, triangular, star, ribbed, square or an shape irregular along its longitudinal length. The radial size of the propellant chamber may taper along its longitudinal direction. The polymeric casing body and propellant insert may be formed of the same or different polymeric materials. The propellant chamber may be formed of a separate propellant insert disposed within the internal cavity of the generally cylindrical hollow polymer body.

The present invention provides a subsonic ammunition case having a polymeric casing body comprising a generally cylindrical hollow polymer body having an body base at a first end thereof and a mouth at a second end to define a propellant chamber; a propellant insert positioned in the propellant chamber to reduce the internal volume of the propellant chamber, wherein the propellant chamber has an internal volume that is between 25 and 80% less than the open internal volume of a standard casing of equivalent caliber; a primer insert positioned at the body base and in communication with the propellant chamber; and a primer disposed in the primer insert in combustible communication with the propellant. The internal volume may be about 25.1, 25.2, 25.3, 25.4, 25.5, 25.6, 25.7, 25.8, 25.9, 26.0, 26.25, 26.5, 26.75, 27, 27.5, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80% and incremental variations thereof or less than the open internal volume of a standard casing of equivalent caliber.

The present invention includes a subsonic ammunition case propellant insert which is adapted to fit in a propellant chamber of an ammunition case to reduce an internal volume between 25 and 80% less that of a standard casing of equivalent caliber, wherein the propellant insert houses a propellant and allows combustible communication between a primer and a projectile.

The present invention includes a method of preparing a subsonic ammunition by providing subsonic ammunition comprising a polymeric casing body comprising a generally cylindrical hollow polymer body having a body base at a first end thereof and a mouth at a second end to define a propellant chamber; a propellant insert positioned in the propellant chamber to reduce the internal volume of the propellant chamber, wherein the propellant chamber has an internal volume that is between 25 and 80% less than the open internal volume of a standard casing of equivalent caliber; connecting a primer insert having a flash-hole to the body base to allow communication between the propellant chamber and the flash hole; inserting a primer disposed in the flash-hole in combustible communication with the propellant chamber; disposing a propellant within the propellant chamber; and inserting a projectile in the mouth to allow combustible communication with the propellant.

The present invention includes a subsonic ammunition having a substantially cylindrical hollow polymeric casing body comprising a polymeric middle body connected to a polymeric bullet-end and a polymeric coupling end to define a propellant chamber; a primer insert connected to the polymeric coupling end to partially seal the substantially cylindrical hollow polymeric casing body, wherein the primer insert comprises a top surface opposite a bottom surface and a substantially cylindrical coupling element that extends from the bottom surface and couples to the polymeric coupling end, a primer recess in the top surface that extends toward the bottom surface, a primer flash hole positioned in the primer recess to extend through the bottom surface, and a flange that extends circumferentially about an outer edge of the top surface; a propellant insert positioned in the propellant chamber to reduce the internal volume of the propellant chamber, wherein the propellant chamber has an internal volume that is between 25 and 80% less than the open internal volume of a standard casing of equivalent caliber; a propellant disposed and confined within the propellant chamber; a primer disposed in the primer recess in combustible communication with the propellant through the primer flash hole; and a projectile frictionally fitted in the mouth in combustible communication with the propellant. The polymeric coupling end may extend over the substantially cylindrical coupling element and covers an circumferential surface to form the primer flash hole.

