Diverging central bore for firearm sound suppressor

Abstract

An apparatus and methods are provided for a front plate having a diverging central bore for firearm sound suppressors that improves noise and flash characteristics during firing a weapon. The central bore is disposed between a back surface and a front surface of the front plate. An untapered portion of the central bore extends from the back surface to a diverging portion that opens toward the front surface. The diverging portion includes a curvature profile configured to allow for more controlled expansion of high-pressure propellant gases exiting of the suppressor through the central bore. The curvature profile provides an included angle of the central bore that decreases secondary flash events accompanying the expulsion of propellant gases accompanying a fired bullet exiting the suppressor through the central bore. The curvature profile exhibits a cross-sectional area of the central bore that is proportional to a distance along the diverging portion.

What is claimed is: 
     
         1 . A front plate for a suppressor for coupling with a muzzle end of a barrel of a firearm for reducing muzzle blast and eliminating muzzle flash, the front plate comprising:
 a central bore disposed between a back surface and a front surface;   a converging portion of the central bore extending from the back surface;   a diverging portion of the central bore opening through the front surface; and   a recess disposed annularly between an outer lip and the central bore.   
     
     
         2 . The front plate of  claim 1 , wherein the converging portion meets the diverging portion within an interior of the central bore. 
     
     
         3 . The front plate of  claim 2 , wherein the converging portion comprises a smooth surface beginning at a start angle with respect to the back surface. 
     
     
         4 . The front plate of  claim 3 , wherein the converging portion meets the diverging portion at a location within the central bore having a tangent angle with respect to a longitudinal axis of the central bore. 
     
     
         5 . The front plate of  claim 4 , wherein the tangent angle comprises an end angle of the converging portion and comprises a start angle of the diverging portion. 
     
     
         6 . The front plate of  claim 5 , wherein the converging portion meets the diverging portion with a non-tangent angle. 
     
     
         7 . The front plate of  claim 5 , wherein the converging portion and the diverging portion are discontinuous. 
     
     
         8 . The front plate of  claim 5 , wherein the converging portion and the diverging portion comprise a combination of multiple straight and/or curved profiles. 
     
     
         9 . The front plate of  claim 5 , wherein the converging portion smoothly blends with the diverging portion to maintain an attachment of propellant gasses to the walls of the central bore during transiting the length of the central bore. 
     
     
         10 . The front plate of  claim 9 , wherein any one or more of the converging portion, the diverging portion, the start angle, the end angle, and the overall length of the central bore can be manipulated to tune the performance of the front plate. 
     
     
         11 . The front plate of  claim 1 , wherein the converging portion extends from a backmost surface of the front plate and meets the diverging portion within an interior of the central bore. 
     
     
         12 . The front plate of  claim 11 , wherein the converging portion extends from a point inset from the backmost surface of the front plate and meets the diverging portion within an interior of the central bore. 
     
     
         13 . The front plate of  claim 11 , wherein the converging portion comprises a straight bore. 
     
     
         14 . The front plate of  claim 11 , wherein the backmost surface is disposed proximal of the back surface by an offset distance. 
     
     
         15 . The front plate of  claim 14 , wherein the offset distance gives the central bore an overall nozzle length that is greater than the distance between the back surface and the front surface of the front plate. 
     
     
         16 . The front plate of  claim 14 , wherein the converging portion comprises a throat area of the central bore at the backmost surface. 
     
     
         17 . The front plate of  claim 16 , wherein the diverging portion comprises an exit area of the central bore at the front surface. 
     
     
         18 . The front plate of  claim 17 , wherein desirable expansion, speed, and/or turbulence properties of propellant gases transiting the central bore can be obtained by manipulating any one or more of the throat area, the exit area, a ratio of throat area to exit area, the offset distance, the overall nozzle length, or any combination thereof. 
     
     
         19 . The front plate of  claim 17 , wherein the throat area and the exit area are configured to produce a desired ratio between a mass flux of the propellant gases transiting the central bore and the mass flux of the propellant gases exiting an annular exit area comprising peripheral vents surrounding the front plate. 
     
     
         20 . The front plate of  claim 17 , wherein the throat area and the exit area are configured to produce a desired ratio between a mass flux of the propellant gases transiting the central bore and the mass flux of the propellant gases exiting an annular exit area comprising a plurality of peripheral vents surrounding the central bore.