This is the probably the answer and what I've found to be the biggest culprit of inconsistency. Also another thing I see that helps is to pause at the end of stroke for a couple seconds. It gives the brass time to completely conform. It's common to dwell at the end of stroke in metal forming operations and I find it helps me when sizing. I did a test a while back sizing 10 pcs quickly then 10 with a pause and the ones done quickly were all over the place. As far as lubing, I see the best results when using a lube pad and rolling 10 or so peices on it instead of spray or sizing wax. There are a lot of variables and some you can't control. You just have to control all you can and do what you do the same every time. I have also started annealing after every firing. It has helped with sizing consistency also as well as the neck tension benefits.
