depending on the maker there is sometimes new old stock out there. They might be able to replace the barrel if they so desire.
Dixie gun works
log cabin shop
track of the wolf
are a few vendors of this sort of stuff.
Little nicks and scratches on a Glock are a bit like a scar on a man’s face, they add panache, unlike a scratch on a otherwise pristine S&W pre 27 .357 or a scar on a woman’s face, which just makes you cringe a little.
remove the bolt and color the rails with a sharpie. Replace the bolt and work it through a cycle, look at the bolt rails and see if there are any places where the sharpie wore off indicating a high spot. Judiciously buff down any high spots.