Bob, only you can or should make that call. Me? If the pits aren't gaping holes in the bore, especially in the first 8 or 10 inches, I'd buy the RST's and have at it. To ease your mind perhaps you should remotely fire a half dozen rounds. Tie it to a tire or something like that and pull a string.

When an old man dies a library burns to the ground. (Old African proverb)