It seems that since Mississippi changed their "primitve weapons" season rules, all of the big bores have been in short supply, sort of a big black hole that sucked all of em out of the system!! Gallery of Guns use to have the .500 and .45-70 in stock regularly, but they haven't for quite some time. If I wanted one, I'd order one at Walmart, then at least you could get on a waiting list as their supplier fills orders on a first come, first served basis.
Tim