I don't know a thing about Biden's background or education, but I can assure you he is not stupid. He is an actor, playing a role designed to win the trust and affection of blue collar working folks. He only has to appear as intelligent as the dumbest guy on a bar stool at that little beer joint three blocks from the Ford factory.
He plays his role well and his 'get a shotgun' comment plays well with working stiffs, farm folks and even a few of us who have used a shotgun in an anti-personnel role and know what it is capable of. Do you need thirty rounds to defend your castle? Probably not. Biden is hoping nobody gives it any thought beyond that point.
Politicians can SAY anything. It is what they DO that is really important, and since Vice Presidents don't DO anything, I wouldn't worry about what Biden says. He is irrelevant. He can't vote in the Senate unless there is a tie, so then watch out, but until then, forget about Biden. Worry about your Reps, Senators, Governors, state elected officials, and OBAMA, and his appointed JUDGES, and agency heads.