I know that most parts such as trigger, grip safety, main spring housing etc. can be replaced with after market parts. But can the double spring recoil guide rod and barrel be replaced with after market parts and does it require much hand fitting? Are there after market springs available for the double spring recoil system? Also, since this is an older WA mfg. all stainless gun will there be a galling problem? I ask because I have an opportunity to purchase a Scoremaster but I want to know what I'm getting myself into first. Thanks guys.