And you don't even need a background check to buy a black powder firearm. Walk into your local Cabela's with a couple of hundred bucks, walk out with one ready to shoot. If you're old enough to grow a beard they probably won't even ask to check your ID to see if you're over 18.
The ATF has repeatedly stated they're not interested in regulating these "historical" items. Never mind swords and bows, a lot of men have been put in pine boxes by a sloppily cast ball of lead coming out of a Patterson or a Remington. Just, probably mostly between the years of 1836 and 1901.