Finally took my 9mm build to the range and was disappointed to have failures to fire. Initially the first 20 or so rounds were like clockwork, my build consisted of a 10.5 psa lightweight mlok upper with hybrid bolt, lower is a psa glock non-LRBHO using a 7.5oz buffer with ar10 buffer tube spring. I changed the buffer weight to standard and spring as well and still was getting light primer strikes. All ammo used was factory winchester and remington.
At home I loaded a round to the chamber, removed the upper from the lower and noticed the round was not against the bolt face. There was a gap between the round and bolt face. I carefully removed the bolt from upper and gently pushed the round into the bolt and it snapped in. My guess is the extractor spring is too strong, the extractor is defective, or the chamber in the barrel is cut to deep. I am putting my bet on a deep chamber.