I happen to have 2 550s one a B one a C...one large primer the other small primer. Have a 750 set up right now for 38/357. Next up is 223. Also have a 1050 in 45 auto. Think I will sell it. Going to load about 2000 rounds first though. I don't shoot as much 45 as I used to and it easily loads 1000 rounds an hour