Quote Originally Posted by BTSniper View Post


Now after firing the full power round the case measures 2.645, after resizing again all the way to the base with the 500 S&W FL die the case has grown/lengthened to 2.660 and of course my head space is too tight now, not allowing the case to chamber.

BT
I'd say your FL die is oversizing the brass creating a excessive head clearance issue, not a headspace issue. When FL sizing the brass can't move back(shellholder) or out (die walls) so it moves forward lengthening a case and the more the body is sized the more a case lengthens.

I'll bet if you back off the die then size a case an 1/8" at a time you can watch it grow like a Chia Pet. You have two choices, trim to length after FL sizing or have that or another die honed to minimum resize your brass.

Bill