Man, that's P-F for you. I spent the morning at the range, and returned to this excellent question. But everyone already knocked it out of the park. I've actually seen more problems with high-dollar ARs that are trying to make the platform do something special than I have with consumer-grade guns like yours. I agree that a quality BCG, and an inspection of a few key areas is probably good enough. Most parts fail either near the beginning or end of their service life. Your guns are in the early middle of the MTBF curve, so that's good.