I've thought a lot about this before and, "when push comes to shove," I'll be relying on the traditional firearms to protect the ol' homestead...Remington 870, Ithaca 37, a lever action rifle or two, and some handguns.
We don't have to look too far back in history to see how our enemies felt about our use of the shotgun when it came to protecting our troops.
During World War I, the German government issued a diplomatic protest against our use of shotguns, alleging that they were prohibited by the law of war. Part of their protest read that "it is especially forbidden to employ arms, projections, or materials calculated to cause unnecessary suffering." Now remember,
machine guns were being used then, too, but the Germans had greater fear of the shotgun because of the destruction they caused.
When their protest was rejected, the Germans threatened to kill all American soldiers they found armed with a shotgun.
Sure, an automatic or semi-automatic rifle can kill and do a good job of doing it, too, but if you've ever seen it personally, or at least have seen pictures, a shotgun leaves one heckuva messy corpse. Believe me, it's not like you see in the movies. It's worse.
So, with all of my rambling, I think I'll be sticking with my ol' tried and true shotguns with plenty of 00 buck.