If you are chewing through rings but the B/C will pass a tilt test, then it comes down to one of three problems.
1. when you are installing the bolt back into the carrier, you are having a problem. Pull the rings and confirm that all the sharp edges of the rings are aligned to the back of the bolt. The rings are stamp cut, and if you are mix matching the index directions, could be that the rings are catching on each other at compression during insertion, and the problem at hand.
2. Take a good look inside the receiver to make sure that the Key bolt channel does not have an inside bur, or the bolt protruding, and this causing the problem.
3. When the carrier was produced, the first step for the gas chamber section was cut too deep inwards, and as the bolt moves forward at unlock, the end ring is allow to jump out of compression, and is being torn up as it has to be re-compress during lock up.