Not all rifles or barrels are equal, I shoot 3 groove PacNors and tend to get 50-75 fps more then book speed with 1-1.5 grs less and work up and stop at the first even indication of pressure as I'm not dumb.
Just curious how you know your barrel is 50-75 fps faster without knowing the pressures your running? and you say your load work up is stopped when the first sign of pressure is seen, yet everyone you show your brass to says your brass looks fine even without checking the primer pockets or taking case head measurments or looking for case head thinning, is it possible even those you showed your cases to don't know for sure the exact pressures your running?
