Anything shooting cast bullets
Anymore I find myself purchasing cast bullet friendly firearms. I have been able to obtain quite a bit of free lead, and have a pretty good assortment of moulds on hand. One can have a lot of fun at the range for not a whole lot of money shooting them. Figuring 3 cents apiece for primers, and assuming one gets all of his brass back, the cost in expendable components for any of the cartridges I shoot is something like 4 to 8 cents per round.
Last I looked that was less than 22 long rifle -- if you can find it.
Cartridges presently under use include 45 ACP, 357 magnum, 32-20, and 32-40.