So I took my 14.5 (pinned with a2x) out to break it in on Saturday. Lower has had about 200 rounds threw it, upper was brand new.
St-t2 buffer with standard carbine spring
unknown buffer tube, mil spec
15.4 standard BCM barrel w/carbine gas system
First 150 was a mix of my old Norinco (which was all flawless) and HSM .223 55gn plinking ammo. Everything past the 150 was HSM (couldn't resist 180 for 500 rounds).
My first 150 rounds were good to go, no malfunctions of any kind. I let a couple of my buddies try my carbine and they were getting lots of Bolt over base malfunctions. 1 out of 3 or 4 rounds. This was all with a fairly new PMAG that has maybe 100 rounds through it before Saturday. I loaded 1 round in all 4 of my mags (other 3 are old USGI with magpul followers). The bolt wouldn't lock back on any of them. I had no issues at all if I manually cycled the bolt.
I had cleaned the hell out of the rifle the day before And lubed everything with EWL 30w. Once I started to get malfunctions I noticed the bolt itself no longer seemed wet and I had left my lube at home.
Should I just chalk it up to being an idiot and under lubing a new upper. Or might I need to take a lighter buffer to shoot that .223 55gn ammo?
At least I had 0 extraction problems, and I was hitting a barrel at 275yards with just 2 clicks of windage adjustment.

