chokebore

choke.bore

n.（名词）
A shotgun bore that narrows toward the muzzle to prevent wide scattering of the shot.
绞筒：一种向枪口逐渐变窄以防止射出子弹分散过开的猎枪枪膛
A gun with a narrowed bore near the muzzle.
绞筒枪：一种有向枪口逐渐变窄的枪膛的枪