The invention relates to systems, methods and devices for controlling the
dispersion of shot or other projectiles fired from a weapon such as a
shotgun. Embodiments according to the invention employ an inner
cylindrical chamber that is divided at a median transverse plane into
forward and rear sections. The rear section of the chamber tapers toward
the median transverse plane and includes a number of radial vents that
open into an outer chamber that provides one or more gas bypass channels
into the forward section of the tubular chamber. The forward section
tapers toward a forward muzzle opening. When a multiple projectile
load/wad is fired from the weapon, expanding gas is sealed behind the
load until it has advanced past the radial vents at which point, gas is
allowed to expand into the outer chamber resulting in a momentary
pressure drop and reduced propulsion force behind the wad/load. The
relatively light wad decelerates while the much heavier shot continues
forward, rapidly separating from the wad before the wad exits the muzzle.
The wad seals against the tapered bore of the forward section of the
inner chamber blocking the escape of gas from the outer chamber
passageways until sufficient pressure develops to eject the wad from the
muzzle end.