A friend of mine has built a 22BR along with me and he just got his barrel back. He brought me over 100 pieces of new Peterson 6BR brass for me to turn the necks down for him. I have a copy of the reamer print used to make his barrel and it says the chamber neck is .253 and brass should be .248. My question is,... is that a "loaded round" dimension or run the mandrel in and turn to .248?? I tried 2 pieces at .248 and I get .250 with bullet pressed in.