So, the problem: I've put about 200 rounds through this rifle. But I've had sporadic failures-to-extract / failures-to-eject. The problem presents like this:
1. Pull trigger.
2. Bullet exits barrel.
3. Either [BCG does not travel rearward], or [BCG extracts properly, but does not travel rearward far enough to eject round], or [BCG does not properly extract empty case at all].
4. Empty casing is stuck in chamber, and requires mallet and push rod to push out of chamber.
This has happened 3-4 times in 200 rounds.
What is going on here? Is there a burr in the chamber? Could the piston be short stroking due to the anti-tilt buffer?