Hello. I reload for a Cooper .223, single shot. I have obtained my OAL (1.855) using a Hornady OAL gauge. I use an RCBS press. I measure my finished rounds with a Frankford Arsenal Digital caliper with a bullet comparator attached. I am loading a 55 grain Nosler Ballistic Tip. I am having trouble getting my rounds to come out with the same OAL. I have tried an RCBS seater, a Redding seater and a Redding Competition seater. I use brass that are all the same length measured with the caliper. I use bullets that are all the same length, measured with the comparator. My finished rounds come out anywhere from 1.853 to 1.860. The longer loads don't shoot as well as the 1.855 loads. Am I being too picky with wanting all my rounds to come out the same length or is this variance considered okay? Any ideas or suggestions would be greatly appreciated.