Pulled down Federal GMM in .308

Yes. Moreover, the mechanical reason for tracking that measurement in rifle cartridges can be seen on many loaded rounds. It shows up as a little ring mark on the bullet ogive where the seating die pushed it to seat it into the case mouth. As a result, the dimension you actually control during seating is base to ogive and not base to tip with most rifle seating die and bullet combinations.


Emcon5,

What you say is generally true of bulk powders and bulk powders are what are generally used by commercial ammunition makers. Federal, however, says they order their GMM powders special for their purposes, so they are paying more for it and getting something more from it. Based on their own load and performance data it is being held very close to matching canister grade 4064. The fact the 43.5 grain charge weight has remained constant for over 20 years would seem to be another clue if it isn't a coincidence. Even canister grade powders for handloaders aren't held that consistent.
 
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