madsenshooter wrote on Mar 23^rd, 2018 at 4:34pm:

NOTE:  I'VE NOT WORKED UP LOADS WITH THE HIGHER CAPACITY CASES YET, THOUGH I HAVE PREVIOUSLY WORKED UP LOADS IN REGULAR 30-40 CASES.

Not to worry. The undersize cases expand to fit the chamber well before peak pressure is reached - meaning at peak they are already "fireformed" and have greater volume as noted. Given the same chamber and charge, any interior-ballistic difference between cases before and after "fireforming" is generally insignificant.