What`s everyone using for case trimmers? I have a Hornady and I have trouble with varying lengths? I set it for 2.840 for my 7mm STW cases, I take random measurements, some as short as 2.837, some long as 2.845? Is that normal , I realize that`s not much variation but not sure why I get even that much? I was thinking about 1 of the auto trimmers that go off the shoulder of the case? What is the best style of trimmer?