High pressure rifle cartridge with primer
A cartridge that generates higher than typical chamber pressures has an enhanced means of primer retention for retaining the primer in the primer recess of the casing. The means may be a lip folded onto a conical surface, a annular groove to receive deformed primer wall portion material upon detonation, a concavity in the rearward facing wall of the primer, a check valve in the flash tube to inhibit propellant gases from reaching the primer recess, or specifically configured primers with a greater length than diameter and with greater wall thicknesses.
1. A cartridge, comprising:
a cartridge casing formed of a rearward head portion and a casing wall portion extending forwardly from the rearward head portion and defining an interior, the rearward head portion having a rearward primer recess and a flash hole extending to the interior, the casing wall portion defining an open forward mouth,
a bullet seated in the open forward mouth;
propellant disposed in the interior rearward of the bullet; and
a primer seated in the rearward primer opening, the primer having a cup portion with a base portion configured as rearward circular wall portion, a forward extending skirt wall portion unitary with the rearward circular wall portion and defining a primer interior, primer compound disposed in the primer interior, wherein the rearward circular wall portion has an interior surface with a central wall surface portion that projects into the primer interior.
2. The cartridge of claim 1 , wherein the interior surface is directly adjacent the primer compound.
3. The cartridge of claim 1 , wherein the interior surface defines a convex surface of the rearward circular wall portion.
4. The cartridge of claim 1 , wherein the rearward circular wall portion further comprises a concave exterior surface.
5. The cartridge of claim 4 , wherein the concave exterior surface is substantially centered on the rearward circular wall portion and extends inwardly toward the primer interior.
6. The cartridge of claim 1 , wherein, upon detonation of the primer compound, the interior surface is configured to expand outwardly to exert an outward radial force against the rearward primer opening.
7. The cartridge of claim 1 , wherein the rearward primer opening defines an annular groove, and wherein the skirt wall is configured to deform into at least a portion of the annular groove defined by the rearward primer opening.
8. The cartridge of claim 7 , wherein the rearward primer opening has a depth and the annular groove has an annular center that is positioned a distance from a rearward face of the head portion that is less than 40% of the depth of the rearward primer opening.
9. The cartridge of claim 7 , wherein the rearward primer opening has a cylindrical wall surface with an axial length and the annular groove is positioned at the midpoint of the axial length of the cylindrical wall surface.
10. The cartridge of claim 1 , wherein the primer further comprises an anvil seated on the primer interior, wherein the primer compound is disposed between the anvil and the rearward circular wall portion.
11. The cartridge of claim 10 , wherein the anvil defines a concave surface extending toward the rearward circular wall portion, and wherein the primer interior defines a biconcave disc.
12. A primer for ammunition that develops chamber pressures exceeding 75,000 psi, comprising:
a cup portion with a base portion configured as rearward circular wall portion and a forward extending skirt wall portion unitary with the rearward circular wall portion and defining a primer interior, wherein the rearward circular wall portion has an interior surface with a central wall surface portion that projects into the primer interior, and wherein the skirt wall portion is configured to be received in a rearward primer opening of a cartridge casing; and
a primer compound disposed in the primer interior.
13. The primer of claim 12 , wherein the interior surface is directly adjacent the primer compound.
14. The primer of claim 12 , wherein the interior surface is defines a convex surface of the rearward circular wall portion.
15. The primer of claim 12 , wherein the rearward circular wall portion further comprises a concave exterior surface, and wherein the concave exterior surface is substantially centered on the rearward circular wall portion and extends inwardly toward the primer interior.
16. The primer of claim 15 , wherein, upon detonation of the primer compound, the concave interior surface is configured to deform into a non-concave shape.
17. The primer of claim 12 , further comprising an anvil seated on the primer interior, wherein the primer compound is disposed between the anvil and the rearward circular wall portion.