So, I have had a couple AA uppers and a POF and never had an issue with them picking up rounds out of the mag. LRBHO works on an empty mag and everything seems to work fine after the first 3 rounds. BRO billet lower, Mega upper, mid-length gas system(5.56), Pmags. Just needs breaking in or is it a tuning issue? I used the standard position and the open position and same issue.

Does the problem happen during firing, manually cycling, or both?

For every build I do now I tune the gun with the buffer. I have some really weak Russian .223 ammo I use and a set of (4) buffers: Carbine, H, H2 and H3. On the last rifle I built, with the carbine buffer the BCG was traveling too fast so the round didn't have time to pop up in the mag for feeding. The H corrected this but for this particular build I was able to run all the way up to an H3 and still get lock back on the last round with the weak ammo. It has run 100% on XM193 and BH 77 and 50 gr TSX. I had an AA build (lo pro gas block) I did that had weak ejection with the carbine buffer. I found out the op rod wasn't entirely straight and was hanging up. I got a dimpling jig to get the gas block on straight and corrected this. It ran flawlessly with an H2 but wouldn't lock back consistently with an H3.

So what buffer are you running??

Just during firing. Manual cycling it's fine.

That sounds like overgassing, where the bolt is coming back forward too soon for the mag to push the round up into the path of the bolt when it is totally full. How far are empties being ejected? Also, when you pull the bolt all the way back with the charging handle, how much space is there between the bolt face and bolt catch?

Upon looking further, the bottom of the carrier is binding on the brass in the mag. The mag spring tension is enough on the first 3 rounds to drag the carrier. I first said it didn't happen while manually cycling, but in fact it does occur. It won't fully go into battery. I'm going to polish the carrier a bit to see if it helps.

If it still occurs I'd check the buffer, drag causes short stroking.