I have an AR-10, 7mm-08, with a X-Caliber 22” custom Stainless Barrel, 9.5 twist. . This custom built weapon, my son and I built, never ceases to amaze and impress. I’m trying different powders, but so far, IMR-4064 and RL-15 has performed the best, pushing a 139 grain SST. The load is 42.0...