Dustin, I smell a money pit in the making. And the end result is most probably going to be less than satisfactory. Most likely far more will be spent on "fixing" it than the whole gun will be worth. Suggest you leave it as is. The gun could probably handle RST's forever without any problem. At 12" there's not much pressure to worry about. Much as I hate sleeving, if any alteration is done I'd go that route. Least cost and least problems encountered. (Oh, I probably shouldn't have posted--I'm sure no expert, except for often stumbling into the dreaded "money pit")

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