I imagine opening the last 3/8 inch of the bore to .310" to .315" would remove all contact with projectile. A clean square shoulder, where the rifling ends, would be the new crown.

IMHO - The removal of the damaged area of rifling, at the muzzle, would hardly be noticeable. A skilled machinist could do this.

Some of the M1 carbines, that came back from Korea, had this done to remove muzzle-wear and improve accuracy. It seems to work.