Standard rimfire ammunition cartridge cases are constructed from a metallic material (e.g., brass or steel) to give them strength to contain the chamber pressures generated when the ammunition is fired. Some metals used to produce small arms ammunition are produced using materials which are not environmentally safe or recyclable.
An engineered polymer material rimfire small arms ammunition cartridge case and the method for manufacturing the same are described herein. The engineered polymer material may meet the Sporting Arms and Ammunition Manufacturers Institute (SAAMI) and/or Commission Internationale Permanente (CIP) specifications for the design of .22 caliber and other caliber rimfire small arms ammunition cartridges. The ballistic performance of the rimfire small arms ammunition using the described polymer case may meet the SAAMI ballistic performance standards. The cartridge case design may allow the projectile/bullet to snap into place during the loading process after the case is primed and powder is placed in the cartridge case. The rimfire cartridge case may be formed by injection molding or a blow molding process, for example.
a shows a polymer rimfire small arms ammunition cartridge case fitted with a .22 caliber projectile/bullet according to an embodiment of the invention.
b shows a .22 caliber projectile/bullet according to an embodiment of the invention.
a shows a polymer rimfire small arms ammunition cartridge case with locking lip according to an embodiment of the invention.
b shows a polymer rimfire small arms ammunition cartridge case with locking lip and .22 caliber projectile/bullet according to an embodiment of the invention.
c shows a polymer rimfire small arms ammunition cartridge case with locking lip and .22 caliber projectile/bullet according to an embodiment of the invention.
a shows a polymer rimfire small arms ammunition cartridge case head according to an embodiment of the invention.
b shows a polymer rimfire small arms ammunition cartridge case head according to an embodiment of the invention.
c shows a polymer rimfire small arms ammunition cartridge case head according to an embodiment of the invention.
a shows a polymer rimfire small arms ammunition cartridge case with locking lip according to an embodiment of the invention.
b shows a projectile suitable for use with the cartridge case of
Rimfire cartridge cases described herein may be made of an engineered polymer comprising materials which make it strong enough to withstand the interior pressures created by firing any rimfire small arms cartridge case such as the .22 short, .22 long, .22 long rifle, .22 Magnum, .22 Stinger, .22WRF, 5mm Remington Magnum, .17 Hornady Magnum, or .17 Hornady Mach 2 caliber cartridge, or any other firearm using a rimfire firing mechanism to ignite the cartridge priming mixture and the propellant contained in the ammunition cartridge case. A polymer cartridge case may be manufactured to the design specifications of SAAMI and/or CIP to produce a fully loaded rimfire small arms ammunition cartridge (e.g., a conventionally loaded cartridge containing a small arms ammunition priming mixture, a small arms ammunition smokeless powder propellant, and a projectile/bullet).
a shows further details of a polymer rimfire cartridge case 1 according to an embodiment of the invention. A magnification of a cross section of the case body 3 in the area of the case mouth 2 is shown. The case body 3 may include a locking lip 6. The case body 3 may be molded in one piece with a locking lip 6 configuration molded into the case mouth 2. As shown in
In some embodiments the projectile/bullet 5 can be held firmly in place within the case 1 with an adhesive such as a cyanoacrylate acrylic resin. A resin such as cyanoacrylate may be used to create a strong bond between the projectile/bullet 5 and the cylindrical wall 3 of the cartridge case mouth 2. Adhesive may be used in combination with the locking lip 6 so that the locking lip 6 can position the projectile/bullet 5 at a desired depth within the case 1 and the adhesive can secure the projectile/bullet 5.
a and 6b show a polymer rimfire small arms ammunition cartridge case 100 (
While the case 100 of
The cartridge cases discussed above may be formed of a polymer, preferably an engineered polymer which is either injection molded or injection blow molded. The engineered polymer may be formed of a nylon resin. Examples of such nylon resins include PA6, NYCOA 8330™ available from Nylon Corporation of America, and RTP 299DX140551™ (natural) from RTP Co. of Winona, Minn., In order to improve the thermal and mechanical properties of cartridge cases made from such nylon resins, various additives may be added. For example, in one embodiment, a nano-composite material comprises a nylon (PA6) base in which nano-clays which are members of the smectite class of layered silicate or platy minerals are dispersed. The nano-clays may include alumino-silicate particles which are uniformly dispersed in a polymer matrix. Another example of a suitable material may be formed from a NYCOA 8330™ base and carbon nanotube (CNT), basalt and/or silica nanoparticle additives. In one embodiment, either CNT, basalt or silica nanoparticle additives are present with weight percentages between 0.25-5, and more preferably 0.5, 1, 1.5 or 2 weight percent. Yet another example includes an RTP 299DX140551 base and additives comprising ball-milled ceramic fibers available from Thermal Products Co. of Norcross, Ga. or powdered KEVLAR™ fibers. Beads of such polymers may be molded into the cartridge case components discussed above using an injection molding or blow molding process. In some embodiments, the material flexibility is sufficient to allow the mouth of the cartridge case to accept a bullet/projectile with an annular groove engaged by a corresponding detent in the cartridge mouth.
Engineered polymers may save natural resources and may be more recyclable than metals. The nano-polymer variants combined to form the case may allow the pressures experienced by the case to equal and/or exceed the pressures experienced in the firing of conventional brass or steel cased .22 rimfire ammunition. The finished engineering polymer cartridge case may equal and/or exceed the ballistic performance of metallic .22 rimfire casings. The nano-composites and/or other materials discussed above may provide the cartridge case with high stiffness which may be comparable to metallic materials. This may provide the ability to produce thin walls and light weight ammunition. Engineering polymers may provide favorable reaction to high heat distortion temperatures and high retention of mechanical properties under humid conditions. Nano-composites and/or other materials discussed above may make the case material inherently fire retardant. Additionally, polymers used for the case may have explosive/propellant compatibility and may prevent moisture absorption while providing moisture protection given to the complete round of ammunition.
While various embodiments have been described above, it should be understood that they have been presented by way of example and not limitation. It will be apparent to persons skilled in the relevant art(s) that various changes in form and detail can be made therein without departing from the spirit and scope. In fact, after reading the above description, it will be apparent to one skilled in the relevant art(s) how to implement alternative embodiments.
In addition, it should be understood that any figures which highlight the functionality and advantages are presented for example purposes only. The disclosed methodology and system are each sufficiently flexible and configurable such that they may be utilized in ways other than that shown.
Although the term “at least one” may often be used in the specification, claims and drawings, the terms “a”, “an”, “the”, “said”, etc. also signify “at least one” or “the at least one” in the specification, claims and drawings.
Finally, it is the applicant's intent that only claims that include the express language “means for” or “step for” be interpreted under 35 U.S.C. 112 (f). Claims that do not expressly include the phrase “means for” or “step for” are not to be interpreted under 35 U.S.C. 112 (f).
This application claims benefit of U.S. Provisional Application No. 62/047,393, filed Sep. 8, 2014, which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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62047393 | Sep 2014 | US |