A:  It is a TV show, with all the PC baggage that goes with it. 

B: However much of their business is real would run a lot smoother without dabbling into FFL record keeping & all the laws that change from state to state.  If I ran their store, I would say NO to post-1898 guns or anything that came close, like most 1898 Krags.

C:  If you were the guy that had all the junk, and if you had a room full of old guns, would you want them on TV?  It is not that hard to figure out where some of the places are.

D:  It is a TV show (again). If you had anything to do with it, would you want to give an opportunity to some crusading troublemaker to cause you legal trouble?