Bolt catching on bolt catch .

[montana]

Bolt face on most ar's are supposed to 1/8" to 1/4" in front of the back edge of the ejection port, if it disappears beyond the back of the port all sorts of wonky malfunctions may occur. On 9mm uppers the bolt face is supposed to stop a 1/4" past the bolt catch.

Thanks for the info, I have never seen an official spec for this measurement. If there is one out there, I would love to see it. SureFire,"designed by Jim Sullivan himself" Optimized Bolt Carrier Group, cut the gas key on their BCG, shortened the buffer and elongated the cam groove.. This allows more recoil travel and dwell time, creating more energy to strip the round from the magazine.. https://www.youtube.com/watch?v=BBVtx8zUcF8