If you want to watch an exercise in frustration, look at the above video. So far the nib m11/9 has been flawless (other than the time I tried 9mm hollowpoints). I've got a bunch of Lage and PS uppers that have all been 100% with all sorts of magazines. I recently got the max 11/15 (after a long backorder since they were working on the one for the mac 10) and put about 200 rounds through it. All 200 rounds of pmc x-tac with magpul 30 rounders and a couple of D60 drums fed without a single hiccup. Today I brought it out for the second time and right from the start it had an issue with both drums and all magpul 30 rounders where the bolt flies forward, but it pushes the round forward maybe half a centimeter and stops. If I cock the bolt back again (it's only a little forward) and fire, it'll always push that round the rest of the way and fire it. How many rounds it gets through before the same kind of stoppage seems random. Usually it's a few rounds, but every now and then it's 20+ rounds. Maybe all the lube burned off on the first session and I just need to slather it in TW-25? The gas seems tuned correctly as the jams are right off a fully cocked bolt, not just while firing.