I am reloading 168 grand Barnes TTSX in 300 win mag. I have trimmed my cased to 2.594". I am using 76 grains of IMR 7828. My press is RCBS with RCBS dies. I have noticed that my COAL is ranging from 3.294 to about 3.323. I am not adjusting the press or die in between loads. My question is: Why am i getting different COAL when the die and press are locked into place?