Firearm Cartridge, Percussion Nipple and Forming Tool Therefor

Abstract

The firearm cartridge has an upper chamber adapted to house gunpowder and a bullet, a lower pocket adapted to house a primer, and a flash hole extending there between. The lower pocket has a ledge disposed generally perpendicularly to the flash hole. The flash hole is formed with a perimeter wall that has a convex curvature adjacent to the ledge of the primer pocket. Likewise, a percussion nipple adapted for use in a black powder rifle has an elongated bore formed with relatively larger and smaller diameter portions connected by a shoulder, and the shoulder has a convex curvature adjacent to the larger diameter portion of the bore. The tool for forming the foregoing shapes has a tip provided with a concave curved surface corresponding to the convex curvature of the flash hole perimeter wall on the cartridge or to the convex curvature of the shoulder in the elongated bore of the percussion nipple.

1 . In a firearm cartridge having an upper chamber adapted to house gunpowder and a bullet, a lower pocket adapted to house a primer, a flash hole extending between the upper chamber and the lower pocket, said lower pocket having a ledge disposed generally perpendicularly to the flash hole, said flash hole being defined by a perimeter wall, that improvement which comprises: said flash hole perimeter wall having a convex curvature adjacent to the ledge of the primer pocket. 
     
     
         2 . The firearm cartridge according to  claim 1 , wherein the convex curvature of said perimeter wall is a mathematically derived shape. 
     
     
         3 . The firearm cartridge according to  claim 2 , wherein the mathematically derived shape of said perimeter wall is one of a set comprising arcuate, parabolic, elliptical, Von Karmen, Haack, and power series. 
     
     
         4 . The firearm cartridge according to  claim 1 , wherein the convex curvature of said perimeter wall extends from the primer pocket ledge to the upper chamber of the cartridge. 
     
     
         5 . In a percussion nipple adapted for use in a black powder rifle, said percussion nipple having an elongated bore formed with relatively larger and smaller diameter portions connected by a shoulder, that improvement which comprises: said shoulder having a convex curvature adjacent to the larger diameter portion of the bore. 
     
     
         6 . The percussion nipple firearm cartridge according to  claim 5 , wherein the convex curvature of said shoulder is a mathematically derived shape. 
     
     
         7 . The percussion nipple according to  claim 6 , wherein the mathematically derived shape of said shoulder is one of a set comprising arcuate, parabolic, elliptical, Von Karmen, Haack, and power series. 
     
     
         8 . The percussion nipple according to  claim 5 , wherein the convex curvature of said shoulder extends from the larger diameter portion to the smaller diameter portion of said elongated bore. 
     
     
         9 . A tool for forming one of a set comprising:
 a firearm cartridge having an upper chamber adapted to house gunpowder and a bullet, a lower pocket adapted to house a primer, a flash hole extending between the upper chamber and the lower pocket, said lower pocket having a ledge disposed generally perpendicularly to the flash hole, said flash hole being defined by a perimeter wall, and said flash hole perimeter wall having a convex curvature adjacent to the ledge of the primer pocket; and   a percussion nipple adapted for use in a black powder rifle, said percussion nipple having an elongated bore formed with relatively larger and smaller diameter portions connected by a shoulder   said tool having a tip formed with a concave curved surface corresponding to the convex curvature of the flash hole perimeter wall of the firearm cartridge or to the convex curvature of the shoulder in the elongated bore.