Firearm bore structure

Abstract

The freebore section of a barrel of a firearm includes a plurality of freebore pads interleaved with a plurality of freebore slots for conveying propellant gases past the bullet upon entry of the bullet into the freebore section to stabilize and maintain the bullet in axial alignment with the axis of the rifled bore of the barrel upon entry of the bullet into the rifled bore.

I claim:  
     
         1 . A barrel for a firearm including a chamber, a free bore, a converging conical section and a rifled bore having a plurality of rifling lands, said barrel comprising in combination: 
 a) a plurality of freebore pads; and    b) a plurality of freebore slots interleaved with said freebore pads, each freebore slot of said plurality of freebore slots extending from said chamber in axial alignment in the alternative with one end of said rifling lands or said rifling grooves.    
     
     
         2 . A barrel for a firearm as set forth in  claim 1  wherein each freebore slot of said plurality of freebore slots terminates in said converging conical section.  
     
     
         3 . A barrel for a firearm as set forth in  claim 1  wherein the radial distance from the longitudinal axis of said barrel to each freebore pads of said plurality of freebore pads is more than the radius of the bore of said barrel.  
     
     
         4 . A barrel for a firearm as set forth in  claim 3  wherein each freebore slot of said plurality of freebore slots terminates in said converging conical section of said freebore.  
     
     
         5 . A barrel for a firearm as set forth in  claim 1  wherein said plurality of freebore slots terminate in said converging conical section at a location commensurate with the diameter of the bullet to be fired through said barrel.  
     
     
         6 . A method for discharging a bullet from a chamber of a barrel of a firearm through a freebore section into the rifled bore of the barrel, said method comprising the steps of: 
 a) limiting lateral movement of the bullet through the freebore section with a plurality of freebore pads circumferentially displaced within the freebore section; and    b) channeling propellant gases alongside and past the bullet through a plurality of freebore slots interleaved with the freebore pads.    
     
     
         7 . The method as set forth in  claim 6  including the step of terminating the flow of the propellant gases past the bullet prior to engagement of the bullet with the rifling of the bore.  
     
     
         8 . The method as set forth in  claim 6  including a converging conical section disposed in the barrel and including the step of terminating flow through the freebore slots in the converging conical section.  
     
     
         9 . The method as set forth in  claim 6  including the step of creating a circumferentially uniformly pressurized propellant gas environment about the nose of the bullet as it becomes engraved by the rifling in the bore.  
     
     
         10 . The method as set forth in  claim 6  including the step accommodating flow of propellant gases intermediate the bullet and the freebore pads prior to entry of the bullet into the rifled bore.  
     
     
         11 . The method as set forth in  claim 6  including the step of urging the propellant gases to exerting a uniform pressure about the nose of the bullet prior to entry of the bullet into the rifled bore.  
     
     
         12 . The method as set forth in  claim 6  including the step of applying the propellant gases under pressure to align the longitudinal axis of the bullet with the longitudinal axis of the rifled bore.  
     
     
         13 . A firearm for accurately firing bullets, said firearm comprising in combination: 
 a) a barrel having a rifled bore formed of rifling lands and rifling grooves, said rifling lands being tapered toward the breach end of said barrel;    b) a chamber for receiving a bullet prior to discharge of propellant gases from a cartridge supporting the bullet;    c) a freebore section disposed in said barrel adjacent said chamber;    d) a converging conical section disposed intermediate said freebore section and said rifled bore; and    e) a plurality of freebore pads interleaved with a plurality of freebore slots disposed in said freebore section for conveying propellant gases past the bullet as the bullet enters said freebore section upon discharge of said firearm.    
     
     
         14 . A firearm as set forth in  claim 13  wherein said freebore slots are in axial alignment with corresponding ones of said rifling lands.  
     
     
         15 . A firearm as set forth in  claim 13  wherein said freebore slots are in axial alignment with corresponding ones of said rifling grooves.  
     
     
         16 . A firearm as set forth in  claim 13  wherein said freebore slots terminate in said converging conical section.  
     
     
         17 . A firearm as set forth in  claim 16  wherein said freebore slots terminate at a location within said converging conical section having a diameter coincident with the diameter of the bullet.  
     
     
         18 . A firearm as set forth in  claim 13  wherein said freebore pads comprise diametrically opposed pairs of freebore pads.  
     
     
         19 . A firearm as set forth in  claim 18  wherein the diameter of each pair of said freebore pads is greater than the bore of said barrel.  
     
     
         20 . A firearm as set forth in  claim 13  wherein each of said freebore slots includes a radially inwardly oriented ramp.  
     
     
         21 . A firearm as set forth in  claim 20  wherein said ramp is radially oriented.