Patent ID: 7523581

Claim:
A shot pattern control system for a multiple projectile load firing weapon that is sealed by a wad, the shot pattern control system comprising: an inner cylindrical chamber that is divided at a median transverse plane into forward and rear sections wherein the rear section tapers toward the median transverse plane, an outer chamber that surrounds the inner chamber and that provides a bypass channel to convey propulsion gas into the forward section of the inner chamber and; a plurality of radial vents that open from the rear section of the inner chamber into the outer chamber; wherein the propulsion gas is initially sealed behind the wad for the multiple projectile load until the wad has advanced past the radial vents; wherein the plurality of radial vents are positioned such that propulsion gas expands into the outer chamber after the wad has advanced past the radial vents; and wherein the forward section of the inner chamber is dimensioned to sealingly engage the wad after it has advanced past the radial vents to cause gas pressure in the outer chamber to build.