Sounds as if you've got a good pressure margin, Ron.

Andreas - To use this method, you will need a good mic with blades, not round anvils. measure right in front of the rim on a marked spot - before and after the shot. Expansion there of .00005 is about max. That's 5, 100/thousanth's.

Measuring this way is not an accurate method - the accurate methodis using pressure equipment. Measuring using expansion is the only method most of us use and over time, we gain a 'feel' for it. There is no quick-route to experience with this stuff. Primers are the worse pressure method to use.

They used to say measure on the rim, and that would be OK as long as it was in a spot where the extractor didn't touch. With modern 63,000PSI rounds, they'd allow as much as .001 on the first firing, then .0005 after that - somthing around these figures. The third firing should not expand the brass at all, due to work hardening of the brass's head. This work hardening is why you should not use old brass for developing loads in any rifle. It will withstand loads that new brass won't (primer pocket expansion). If you do use old brass, then some day you'll buy some new, unfired brass & your first shot using your worked up maximums could fill your face with powder gasses and burning particals, tie up the action - or worse. Once metal starts to move, all H$ll can break loose.