Finally shot mine for the first time today after buying it back in November of last year (I know, November......
?). Since it was an early gun (S/N in the mid-1000s) and came with 3 gen 2 Pmags, I was expecting failures. I was surprised to find that I only had one failure to feed, and that was with the new metal DPMS mag that I brought because that was supposedly the "fix" for the early ones. All 3 of the Gen 2 Pmags, as well as a 10rd Gen 3, ran perfectly. Tried M852 Match, old Hansen (Yugo) 147 gr., and German MEN 86 ammo. Everything that fed went boom, and all shooting was done with the gas regulator on the normal 2 position.
I suspect the single failure was a problem with the DPMS mag. It was the next to last round in the mag, and the bullet nose may have dragged on the inside of the mag. Used other mags for the rest of the shoot, and it ran fine.