초록

A firearm cartridge is provided with a case body and a piston head. The piston head is movably engaged with a rearward end of the case body. The piston head seals the rearward end of the case body to contain propellant gases in the case body when the firearm cartridge is fired.

대표청구항 ▼

What is claimed is: 1. A firearm cartridge, comprising: a case body including a wall extending between a forward end and a rearward end, said case body wall defining a hollow interior and propellant in said hollow interior; and a piston head including a forward end positioned in said hollow interio

What is claimed is: 1. A firearm cartridge, comprising: a case body including a wall extending between a forward end and a rearward end, said case body wall defining a hollow interior and propellant in said hollow interior; and a piston head including a forward end positioned in said hollow interior adjacent said rearward end of said case body and with propellant forwardly of said forward end of said piston head and further comprising priming composition in a recess between an outer surface of said piston head and said wall of said case body, said piston head being rearwardly movable relative to said case body via pressure from firing the firearm cartridge. 2. The cartridge of claim 1, wherein said piston head is fixedly engaged to said rearward end of said case body, and when the firearm cartridge is fired said piston head is disengaged from said case body for movement rearwardly relative thereto in sealing engagement with said wall of said case body. 3. The cartridge of claim 1, wherein said rearward end of said case body includes a fold portion crimpable to engage said piston head. 4. The cartridge of claim 3, wherein said piston head includes a groove extending thereabout, said groove being located between a forward end and a rearward end of said piston head, said fold portion being crimpable into said groove. 5. The cartridge of claim 4, wherein said piston head includes an intermediate flange extending radially about a rearward side of said groove. 6. The cartridge of claim 1, wherein said piston head includes a flange in said hollow interior spaced rearwardly of said forward end of said piston head, said piston head further including a groove extending forwardly of said flange to said forward end of said piston head. 7. The cartridge of claim 6, wherein said groove forms said recess along said wall of said case body. 8. The cartridge of claim 1, wherein said forward end of said piston head includes a concave recess in communication with propellant in said case body. 9. The cartridge of claim 8, wherein said concave recess receives pressure from the firearm cartridge when fired and is structured to radially expand said piston head in slideably sealing engagement with said case body. 10. The cartridge of claim 1, wherein said piston head is integrally formed with said case body. 11. The cartridge of claim 1, wherein said piston head includes a flange in said hollow interior spaced rearwardly of said forward end of said piston head, said piston head further including a grooved portion extending rearwardly from said flange, said grooved portion receiving a rearward end of said case body. 12. The cartridge of claim 11, wherein said rearward end of said case body includes a shoulder engaged to said piston head in said grooved portion, and further comprising a gap formed by said piston head and said wall of said case body, said gap extending between said shoulder and said flange. 13. The cartridge of claim 12, wherein said gap accommodates rearward movement of said piston head relative to said case body when the firearm cartridge is fired. 14. The cartridge of claim 12, wherein said shoulder of said case body is formed by inwardly folding said wall of said case body at said rearward end of said case body, thereby forming a space between said shoulder and said wall of said case body. 15. The cartridge of claim 12, wherein said shoulder includes a forwardly oriented chamfered end wall. 16. A firearm cartridge, comprising: a case body including a wall extending between a forward end and a rearward end, said case body wall defining a hollow interior; and a piston head including a forward end positioned in said hollow interior adjacent said rearward end of said case body in said hollow interior, said piston head including a flange extending therearound engageable with said wall of said case body, said piston head further including a groove extending forwardly of said flange, said groove and said wall of said case body defining a recess; and priming composition in said recess. 17. The cartridge of claim 16, wherein said piston head is rearwardly movable relative to said case body when the firearm cartridge is fired. 18. The cartridge of claim 16, wherein said piston head is fixedly engaged to said rearward end of said case body, and when the firearm cartridge is fired said piston head is unfixed from said case body for movement rearwardly relative thereto in sliding engagement therewith. 19. The cartridge of claim 16, wherein said rearward end of said case body includes a fold portion engaged to said piston head. 20. The cartridge of claim 19, wherein said piston head includes an intermediate groove extending thereabout, said intermediate groove being located between a forward end and a rearward end of said piston head, said fold portion being engaged in said intermediate groove. 21. The cartridge of claim 16, wherein said forward end of said piston head includes a concave recess in communication with propellant in said case body. 22. The cartridge of claim 21, wherein said recess receives pressure from the firearm cartridge when fired and is structured to radially expand said flange of said piston head in sealing engagement with said case body. 23. The cartridge of claim 16, wherein said piston head is integrally formed with said case body. 24. The cartridge of claim 16, wherein said piston head includes a grooved portion extending rearwardly from said flange, said grooved portion receiving a rearward end of said case body. 25. The cartridge of claim 16, wherein said rearward end of said case body includes a forwardly facing shoulder engaged along said piston head, and further comprising a gap formed by said piston head and said wall of said case body, said gap extending between said shoulder and a rearward face of said flange. 26. The cartridge of claim 25, wherein said gap accommodates rearward movement of said piston head relative to said case body when the firearm cartridge is fired. 27. A firearm cartridge, comprising: a case body including a wall extending between a forward end and a rearward end, said case body wall defining a hollow interior for receiving propellant; and a piston head including a forward end positioned in said hollow interior adjacent said rearward end of said case body, said piston head including a flange extending thereabout and a forwardly opening recess in said forward end in communication with said hollow interior, said piston head being expandable by pressure in said recess created upon firing of the cartridge to seal said flange against an inner surface of said wall of said case body. 28. The cartridge of claim 27, wherein said piston head is rearwardly movable relative to said case body when the firearm cartridge is fired. 29. The cartridge of claim 27, wherein said piston head includes a groove extending forwardly of said flange, said groove forming a second recess with said wall of said case body opening forwardly into said hollow interior, and further comprising a priming composition in said second recess. 30. The cartridge of claim 29, wherein said wall of said case body includes groove in an outer surface thereof aligned with said second recess. 31. The cartridge of claim 27, wherein said recess is concavely curved. 32. The cartridge of claim 27, wherein said rearward end of said case body includes a fold portion, said fold portion including an inner wall member extending along said wall of said case body, said inner wall member including a forwardly facing shoulder. 33. The cartridge of claim 32, wherein said inner wall member forms a space along said wall of said case body. 34. The cartridge of claim 33, wherein said forwardly facing shoulder includes a chamfer. 35. The cartridge of claim 32, further comprising a gap between said forwardly facing shoulder of said case body and a rearwardly facing shoulder of said flange of said piston head, said gap accommodating rearward movement of said piston head relative to said case body upon firing of the firearm cartridge. 36. The cartridge of claim 35, wherein said piston head is rearwardly movable to engage said rearwardly facing shoulder of said flange with said forwardly facing shoulder of said case body and plastically deform said fold portion. 37. The cartridge of claim 27, wherein said piston head includes a primer assembly embedded in a rearwardly oriented face thereof, said piston head further comprising a passage extending therethrough between said primer assembly and said hollow interior of said casing. 38. The cartridge of claim 27, wherein said piston head is integrally formed with said case body. 39. The cartridge of claim 38, wherein said case body includes a fold portion at a rearward end thereof, said fold portion including an inner member extending from said rearward end and forwardly along said wall to said flange of said piston head, said inner member being integrally formed with said flange.