- Sep 23, 2017
I have thousands of Federal GMM large magnum primers that I purchased just as this "covid thing" hit. I have not used them in 308 Winchester yet, but I plan to next year. I was wondering how I should start my load workup? My current best group size is 1/2 moa. Rifle is a DPMS AR10 that was gutted and all parts replaced with the following: silent capture buffer system, Aero Precision BCG, CMC 2+3 trigger, palm swell grip, Black Hole Weaponry tri-polygonal 24" custom fluted barrel, PSA low profile gas block, Heartbreaker muzzle brake, Valdada Anvil bipod, 40mm V-Tac 20moa cantilever mount, and a Valdada Recon G2 optic in moa. Load is: Peterson Cartridge 308 large primer match brass, Federal GMM large primer, 44.2 grs. of Varget, Cutting-Edge 168gr MTAC projectile.