I am new to the AR-15 world, so I hope I am not asking stupid questions. My rifle: Rock River Lower Del-Ton Mid-Length Upper Wilson Chrome Lined Heavy Barrel in 5.56 Ammo: Tulammo 55 gr steel cased Magazines: 30 round gray metal mags with green follower from DPMS and 20 round Thermold mags made in NC Problem: I took the rifle out for the first time today. First 5 rounds fired from 30 round mag fine. Then "click". Bolt did not chamber round. Manual cycled and fired fine, then click on next round. This happened repeatedly. Tried a Thermold mag and all 20 rounds fired without incident. Used another metal mag and it became a single-shot rifle again. Changed to another Thermold and it would fire a couple of rounds then become a single-shot for the rest of the mag. It happened like this with all 5 Thermolds and both DPMS mags. Switched to a Stoner mag (buddies) and had same problem. Took BCG out, stripped, cleaned. Reassembled, fired 10 rounds from Thermold, no problem. Then it started again with both metal mags and Thermold mags, just like before. First thought, something is wrong in the BCG. Put my buddies bolt in, fired 20 rounds no problem from Thermold, so I thought problem is bolt. SO, I put my bolt back in and it fires 17 rounds fine from Thermold, but then goes to crap again. Changed mags and went back to single-shot rifle. I guess I should have fired more with buddis bolt in to be sure, but I was really aggravated at that point and he had to leave. After he left I shot about 70 more rounds, basically all in single shot mode. My hand really got tired pulling that charging handle so many times. I know some people say Tula ammo is no good, but know other guys who fired same ammo through the RRA lowers with delton uppers with nothing like this happening. Assuming the ammo aint the problem, what should I look at first? Thanks in advance!