Rifled ammunition system

Abstract

Gun and ammunition solutions which permit the use of High Explosive (HE) rounds and Armor Piercing Fin Stabilized Discarding Sabot (APFSDS) rounds in one weapon. A first system has a gun barrel chamber sized to receive the outer cases of both APFSDS and HE rounds. The chamber has a smooth rear section which abuts a front section having internal helical rifling. A HE round has an outer case with a length that is the same as the length of the smooth rear section of the barrel. A projectile held by the case has a rotating band on a rear end configured to engage the internal helical rifling in the chamber. A second system has a conventional smooth barrel and utilizes a HE round with an outer case having internal rifling in a forward section. A projectile held by the outer case has a circular band mounted to rotate about a rear end thereof to engage the internal rifling.

What is claimed is: 
     
         1 . A firearm system for use with both armor-piercing and high explosive rounds, comprising:
 a chamber between a breach and a barrel, the chamber having a diameter sized to receive the outer cases of both armor-piercing and high explosive rounds, the chamber having a smooth rear section which abuts a front section having internal helical rifling.   
     
     
         2 . The system of  claim 1 , wherein the front section has a length of about half of the chamber length. 
     
     
         3 . The system of  claim 2 , wherein the chamber length is between 8-15 inches. 
     
     
         4 . The system of  claim 2 , wherein the front section is straight and the rear section is tapered. 
     
     
         5 . The system of  claim 1 , wherein the front section is straight and the rear section is tapered. 
     
     
         6 . The system of  claim 1 , further including a high explosive round having an outer case with a length that is approximately the same as a length of the smooth rear section of the chamber of the barrel, and a projectile held by the outer case with a rotating band on a rear end thereof configured to engage the internal helical rifling in the front section of the chamber. 
     
     
         7 . The system of  claim 6 , wherein the rotating band is formed of plastic and has a smooth outer surface. 
     
     
         8 . The system of  claim 1 , further including an armor-piercing round having an outer case with a length that is approximately the same as the chamber length and a sealing ring at a forward end positioned within and sized to engage a smooth bore portion of the barrel forward of the chamber. 
     
     
         9 . The system of  claim 1 , wherein the internal helical rifling has a helix angle of between 20-26°. 
     
     
         10 . The system of  claim 1 , wherein the internal helical rifling is formed by raised helical ribs extending inward within the chamber. 
     
     
         11 . A firearm system for use with both armor-piercing and high explosive rounds, comprising:
 a chamber between a breach and a barrel, the chamber having a diameter sized to receive the outer cases of both armor-piercing and high explosive rounds, the chamber having a smooth tapered rear section which abuts a straight front section having internal helical rifling having a helix angle of between 20-26°.   
     
     
         12 . The system of  claim 11 , wherein the front section has a length of about half of the chamber length. 
     
     
         13 . The system of  claim 12 , wherein the chamber length is between 8-15 inches. 
     
     
         14 . The system of  claim 13 , wherein the chamber length is 12 or 13 inches. 
     
     
         15 . The system of  claim 11 , wherein the chamber length is between 8-15 inches. 
     
     
         16 . The system of  claim 11 , further including a high explosive round having an outer case with a length that is approximately the same as a length of the smooth rear section of the chamber of the barrel, and a projectile held by the outer case with a rotating band on a rear end thereof configured to engage the internal helical rifling in the front section of the chamber. 
     
     
         17 . The system of  claim 16 , wherein the rotating band is formed of plastic and has a smooth outer surface. 
     
     
         18 . The system of  claim 16 , wherein the rotating band is formed of metal and has a smooth outer surface. 
     
     
         19 . The system of  claim 11 , further including an armor-piercing round having an outer case with a length that is approximately the same as the chamber length and a sealing ring at a forward end positioned within and sized to engage a smooth bore portion of the barrel forward of the chamber. 
     
     
         20 . The system of  claim 11 , wherein the internal helical rifling is formed by raised helical ribs extending inward within the chamber.