Well, the new gun is having some problems. It's not ejecting rounds properly. All the rounds extract fully from the chamber, but about 1 out of every 5 fail to eject and end up staying in the ejection port. At first I thought maybe it was a gas system problem and I might have to enlarge the gas port, but I tested it by loading 1 round in the mag and firing. It locked the bolt back on the empty mag each time I tried that, and that's supposed to be a good indication that the gas system is ok and you're not short stroking.
The ejector seems like it has plenty of tension, so I'm actually wondering if it's a problem with the extractor. Compared to the BCM bolt in my other AR, this extractor seems like it has a lot less tension. My theory is that the extractor isn't holding on to the case rim tight enough, and it's falling off the bolt before the ejector has a chance to fling it out of the port. I just ordered an extractor spring upgrade kit from BCM, so hopefully that will take care of it.