Mk12 won’t feed and lock my hand loads. I have Douglas barrel, standard mil bolt carrier with a jp bolt. Hand loads are 77gr smk loaded into surplus standard mil brass. OAL is 2.25. Measured the case and everything seems to be within standards. Same rounds operate fine through my buddy’s rifle with a Daniel defense barrel. I know the tolerances on my barrel should be tighter. Bolt locks if rounds are manually loaded individually but will not lock if a mag is used. Also if loaded manually they are hard to eject manually. I’ve tried brand new p mags as well as the standard garbage ones. Also swapped the bolt carrier already. Must be something in my hand loads that I’m not seeing. Using RCBS small base two die set with Lee single stage press. Appreciate the help.