RST loaded NICE shot it hasn't been availible for a couple of years. I load ITX for my waterfowl and non-toxic upland. Bismuth is available.
Any other loads are readily available by mail order, I keep a couple of cases of Herters 8s a4ound but I do that with my 12 & 20 also. I haven't bought a box of shotgun shells in a store for years.
RIO is loading Bismuth 16 ga shells in 4&6 plus Hevi Shot loads there Classic Doubles in a non-toxic round.
I have some of the Classic doubles and Rio Bismuth for my old guns and reload ITX and bismuth as well. All good stuff for keeping the old ones shooting.