chokebore

(-bôr′)

noun

  1. a shotgun bore that tapers toward the muzzle to keep the shot closely bunched
  2. a gun with such a bore

See chokebore in American Heritage Dictionary 4

noun
  1. A shotgun bore that narrows toward the muzzle to prevent wide scattering of the shot.
  2. A gun with a narrowed bore near the muzzle.
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