Breech seal for air gun

Abstract

A barrel break air gun includes a pair of opposed, generally planar faces defining a narrow gap between the breech and the barrel. The barrel face includes a circular groove concentric with the barrel bore that receives an annular seal, and a recessed annular land defined between the circular groove and the barrel bore. The annular seal may be either an o-ring nominally disposed within the circular groove, or an annular urethane washer that is slightly radially-compressed when placed into the circular groove such that the inner diameter of the washer projects slightly away from the barrel face prior to closing the barrel breech. In one embodiment featuring the annular washer, the washer's internal diameter is slightly smaller than the maximum skirt dimension of an air gun pellet, such that the pellet's skirt is retained by the washer upon closing the barrel breech.

1 . An air gun comprising:
 a receiver having a breech face and defining a gas port configured for exhausting a compressed gas therethrough;   a barrel defining a bore extending along a longitudinal axis of said barrel and including a barrel face disposed opposite said breech face, wherein said bore is in fluid communication with said gas port for receiving the compressed gas;   said barrel defining a circular groove disposed concentrically about and radially offset from said bore and recessed a depth from said barrel face;   a seal at least partially disposed within said circular groove and in sealing engagement with said breech face of said receiver for sealing said bore and said gas port between said barrel and said receiver; and   an annular land disposed adjacent and concentrically about said bore between said circular groove and said bore and recessed from said barrel face a depth less than said recessed depth of said circular groove.   
     
     
         2 . An air gun as set forth in  claim 1  wherein said seal includes a durometer greater than or equal to 40 and less than or equal to 90. 
     
     
         3 . An air gun as set forth in  claim 2  wherein said seal includes an o-ring seal. 
     
     
         4 . An air gun as set forth in  claim 2  wherein said seal includes a washer. 
     
     
         5 . An air gun as set forth in  claim 4  wherein said washer includes a thickness greater than a difference between said depth of said circular groove relative to said barrel face and said depth of said annular land relative to said barrel face. 
     
     
         6 . An air gun as set forth in  claim 5  wherein said washer defines an outer diameter greater than an outer diameter of said circular groove. 
     
     
         7 . An air gun as set forth in  claim 6  wherein said washer defines a radially inner surface having a diameter that is less than a diameter of said bore of said barrel. 
     
     
         8 . An air gun as set forth in  claim 7  wherein said radial inner surface of said washer includes at least one surface feature for contacting a pellet disposed in said bore and configured for providing a consistent breakaway force between the pellet and said bore. 
     
     
         9 . An air gun as set forth in  claim 4  wherein said washer includes a cylindrical body disposed within said circular groove and a flange extending radially inward from said body adjacent said annular land. 
     
     
         10 . An air gun as set forth in  claim 9  wherein said body includes a length along said longitudinal axis that is greater than said depth of said circular groove relative to said barrel face. 
     
     
         11 . An air gun as set forth in  claim 10  wherein said flange includes at thickness greater than said depth of said annular land relative to said barrel face. 
     
     
         12 . An air gun as set forth in  claim 9  wherein said flange defines a radially inner surface having a diameter that is less than a diameter of said bore of said barrel. 
     
     
         13 . An air gun as set forth in  claim 12  wherein said radial inner surface of said flange includes at least one surface feature for contacting a pellet disposed in said bore and configured for providing a consistent breakaway force between the pellet and said bore. 
     
     
         14 . An air gun comprising:
 a receiver having a breech face defining a gas port configured for exhausting a compressed gas therethrough;   a barrel defining a bore extending along a longitudinal axis of said barrel and including a barrel face disposed opposite said breech face, wherein said bore is in fluid communication with said gas port for receiving the compressed gas;   said barrel defining a counterbore disposed concentrically about and adjacent said bore of said barrel; and   a seal at least partially disposed within said circular counterbore and in sealing engagement with said breech face of said receiver for sealing said bore and said gas port between said barrel and said receiver;   wherein said seal includes a cylindrical body extending along said longitudinal axis and a second flange disposed at a second end of said cylindrical body and extending radially inward from said cylindrical body to a radial inner surface having a diameter less than a diameter of said bore.   
     
     
         15 . An air gun as set forth in  claim 14  wherein said counter bore extends a depth along said longitudinal axis relative to said barrel face and said second flange includes a thickness along said longitudinal axis relative to said barrel face that is less than said depth of said counterbore. 
     
     
         16 . An air gun as set forth in  claim 15  wherein said radial inner surface of said second flange includes at least one surface feature for contacting a pellet disposed in said bore and configured for providing a consistent breakaway force between the pellet and said bore. 
     
     
         17 . An air gun as set forth in  claim 16  wherein said seal includes a first flange disposed at a first end of said cylindrical body between said barrel face and said breech face, and extending radially outward from said cylindrical body. 
     
     
         18 . An air gun as set forth in  claim 17  wherein said seal includes a durometer greater than or equal to 40 and less than or equal to 90. 
     
     
         19 . An air gun comprising:
 a receiver defining a gas port configured for exhausting a compressed gas therethrough;   a barrel defining a bore extending along a longitudinal axis of said barrel and including a barrel face, wherein said bore is in fluid communication with said gas port for receiving the compressed gas; and   a seal in sealing engagement with said barrel face and said receiver for sealing said bore and said gas port, and defining an interior diameter less than a diameter of a projectile for engaging at least a portion of the projectile and retaining the projectile in place until fired.   
     
     
         20 . An air gun as set forth in  claim 19  wherein said seal includes a durometer greater than or equal to 40 and less than or equal to 90. 
     
     
         21 . An air gun as set forth in  claim 20  wherein said barrel defines a counterbore disposed concentrically about and adjacent said bore of said barrel, with said seal at least partially disposed within said counterbore. 
     
     
         22 . An air gun as set forth in  claim 20  further comprising loading mechanism configured for urging the projectile into a secured position within said seal. 
     
     
         23 . An air gun as set forth in  claim 22  wherein the loading mechanism is disposed inline with said longitudinal axis, with said seal configured for sealing against a barrel face of said loading mechanism. 
     
     
         24 . An air gun as set forth in  claim 23  wherein said seal defines a port adjacent and in fluid communication with said gas transfer port.