I totally agree with you Dick...  If my family had been killed, I would never even have involved with the show!  I think it's more that the prop guys weren't worried about authenticity!  It wouldn't have been the first time...  Many shows back then were for more entertainment value than anything else. 

By the way, speaking of rifles on TV... did you all know that the first 2 seasons of The Beverly Hillbillies, Jed runs into the cabin after shootin up that oil and lays a 1873 Trapdoor rifle on the table?  He also shoots it in an episode in the first season where he joins Drysdale's gun club!