I clean all fouling out of anything I buy, slug, and record. That way I know what size evrything is and know what to size for for various toys without having to slug it ererytime I want to load some up for them. There is variation between bores, regardless of who the manufacturer is. You may get lucky and get two that are identical, but eventually you will get one that isn't quite "optimum" diameter and that will give you headaches til you slug ut and figure out what it needs to shoot well.