Never tried using small rifle primers, but I have run about 35,000 of small pistol magnum primers (CCI) thru this G17 (about 80,000 rounds total). And the G34 LoneWolf SS upper has about 17,000 of small magnum CCI's also. Looks normal to me. 125 TC Bear Creek on top of 4 grs TiteGroup at 1.155 overall length. Goes about 1,180 fps out of the G17.