Patent ID: 6964220

Claim:
A gun for directing a projectile, said gun compromising: (a) an external barrel having an inner wall forming a hollow interior within said external barrel, said external barrel having a forward end and having a rear end; said external barrel having an internal metal flange extending into said hollow interior and causing said hollow interior of said external barrel to have a narrowed internal diameter thereat; said internal flange having a proximal side remote from said forward end; said external barrel being terminated at said rear end by a metal base extending into said hollow interior; said external barrel containing a detached breech block with a striker housing aperture therethrough; said hollow interior having a firing chamber portion distally adjacent said breech block, said firing chamber portion being adapted for holding a firing cartridge therewithin; (b) a forwardly-slidable internal barrel disposed within said external barrel, said internal barrel being an elongated cylinder of metal having an outer surface and having a distal end and having a proximal end; said internal barrel being open on said distal end and on said proximal end and having an unobstructed bore extending therethrough from said distal end to said proximal end; said internal barrel including an external metal annulus secured thereabout adjacent said proximal end, said annulus having a distal side remote from said proximal end; said distal end of said internal barrel being supported and surrounded by said internal flange of said external barrel; said gun having a forward chamber therewithin bounded by said distal side of said annulus of said internal barrel, by said proximal side of said internal flange of said external barrel, by said outer surface of said internal barrel, and by said inner wall of said external barrel; said gun further having at least one concave groove formed within said internal wall of said external barrel and extending longitudinally from within said firing chamber, past said annulus of said internal barrel, and to said forward chamber; said gun further having at least one passageway void disposed though said metal annulus of said internal barrel; said passageway void having a first opening through said distal side of said annulus and a rearwardly-facing second opening through said proximal side of said annulus.