My AR-10 build had a JP enhanced nickel boron coated bolt that had the extractor pin hole drilled incorrectly and I had to send it back. It was replaced immediately by JP with a non NiB bolt that performed perfectly. Luckily I had a DPMS bolt in the bin to use while I was waiting.
I brought this up in one of the discussions where Epoxy was bashing the MH because it has a DPMS BCG to point out that even the highest regarded companies can have the odd sub standard part make it through QC and get into the hands of it's customers.