I bought two CProducts 10rd magazines for my 6.8. They function great so far, but capacity is different by one round based on ammo manufacturer. Both magazines will hold 9 rounds of Federal Fusion but 10 rounds of Remington Ultra-bonded Corelokt. Both rounds feed/fire/eject in the rifle. Any idea what the difference is? It's got to be case diameter, right? I don't have a caliper to measure the difference at this time, but how far off can they be and still work?