What we're working with:
BCM 11.5" BFH barrel
BCM Lo profile gas block
LMT Enhanced carrier
Stardard bolt w/ Oring on the extractor spring
Vltor A5 (as the kit came, H2 buffer?)
What happened:
Initial firing of the upper using M855 and M193 had the bolt locking back reliably with a nice 4 o'clock ejection. To further evaluate the upper, the rate of fire was increased to rapid and after 60-70 rounds the first malfunction occurred. The spent casing was 3/4 of the way extracted from the chamber and the next round was partially stripped from the magazine and started to feed. At that time a friend noticed the ejection patter moving more towards the 5-5:30 (and some brass residue on the deflector).
Seemed like as the rifle got warm the problem reared up. Going back to basics, the mags were loaded with a single round and the rifle still reliably locked to the rear with a single round. However, anytime the mags were loaded up, the problem as noted above occurred almost each time.
Where should the investigation begin?


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