Try to pass some boretech through it and it'll look like new.
Keep in mind you want SOME fouling in there so it is a good idea to just do a "quick and dirty" style cleaning where you might pass a bore solvent in it but you're not really going after it, so to speak. Otherwise you'll have to do some fouling shots before you're back to your accuracy you expect from the rifle. At 25 yards though, it probably doesn't matter much with fouling shots and you probably won't really notice it.