12-gauge/bore shotgun

12-gauge/bore shotgun不是弹夹(magazine)容量为12发的霰(xian)弹枪。【LDOCE】gauge - a measurement of the width or thickness of sth such as wire or metal. 【牛津】号。与厘米、英寸不同，gauge虽然是度量单位，但在不同语境下有不同的意思。此处gauge描述枪管(barrel)的直径。

【thebiggamehuntingblog稻糠亩】 A 2 bore rifle has a nominal bore diameter equal to the diameter of lead ball weighing 1/2 pound, a 4 bore rifle has a bore diameter of a 1/4 pound lead sphere... the diameter of the barrel on a 12 gauge shotgun is the size of a 1/12 pound lead ball. 质量/比重后，大约等于18.42mm。比重不应该叫比质吗？

词汇联想: gear, gadget, gizmo.

bore有钻孔的意思，有段时间炮膛是钻出来的。