English and American terms
I have often heard the term 'bore' used for describing the size of a weapon by English sources (the James Harriot books use the term when describing shotguns and things like that, as do the books of H. Rider Haggard), and 'gauge' is often used by those of us on this side of the pond. From what I have read, the 2, 4, and 8 bore rifles were used by the big game hunters in Africa, prior to the advent of smokeless powder.
That being said, I'd love to say I shot one, but I'm not sure I actually want to go shoot one.
D