Is there anyway to tell which piston belongs to which cylinder or are the all identical? I ask as i'm considering buying some used pistons/barrels as my old piston rings aren't bedding into my new barrels. Problem being, most sellers appear to have mixed up the pistons so there's no way of knowing which one belongs to which cylinder, any chance the pistons are labelled 1,2,3,4 or is that wishful thinking?