I remember reading a sci-fi novel, forgot which and by whom, but there was a very smart bit in it about the existence. In terms of existence, a hero said, only three numbers make sense: 0, 1 and infinity. That is, something can not exist at all. Or there can be only one such object (a planet with sapient life, in that instance). But if there can be two of something, there can theoretically be an infinite number of this. I think that applies to gun collecting. The minimum useful number of shotguns is 1. As many said before, a 7 pound 12 gauge will do it all. Once you need more than one, you need an infinity.
