Just checkin to see if anyone has one installed and is experiencing a failure to fire rounds like Lake City. My DPMS had the yellow spring and worked fine. The NFA lower I now have won't ignite Lake City rounds. I don't want to put the old spring back in, I hated the feel of it. Felt like dragging your bare ass on textured concrete. (not that i'd know.....) I have like 2000 rounds of LC brass so I can't just give up on the LC stuff. Thinking of changing the lower in the near future, but if anyone else has experienced this and found a way around it please do tell.