Exactly this. "low end" / inexpensive AR parts are cheap for a reason. It may be because of material selection, but you can be guaranteed that their QC will be substandard to the more highly regarded brands. The old "parts are parts" mentality is an absolute fallacy in the AR world. Ash is a certified armorer that works part time in a busy shop. He sees a ton of poorly built factory and home brewed guns. I've seen my fair share, especially in the last 2 years. One of the more common issues that we've both seen this year are improperly assembled barrel extensions and improperly torqued barrel nuts. Both can create excessive headspace. Even if your favorite bargain parts supplier lists a part with the same specs on paper, that doesn't mean it's equivalent to a part that seems identical from a more expensive manufacturer. For example, a bolt may be HP/MPI tested, but they don't tell you what the acceptance criteria and rejection rates are. Another example, a barrel may be mil spec steel, chrome lined, hp/MPI, etc. But you don't know if the chamber would pass a 5.56 chamber gauge, what straightness specs were required, if the barrel extension was properly installed, what size gas port was used, what the testing criteria were, etc. The list goes on and on. Every QC step costs time and money. As mentioned above, I recently saw not one, but two low end guns with hand tight barrel extensions in one day. Another example was an Elite Arms / Bear Creek upper I dealt with about a year ago for a friend. I don't have enough time to explain just how badly screwed up that gun was. No one is perfect and even the "good guys" have a lemon slip out the door occasionally, but I'd guarantee it's miniscule in comparison to the bargain brands. The flood of cheap AR's we've seen in the last couple of years are banking on one thing and one thing only; they think it's OK to sell cheap junk because they don't think the average shooter will use the gun enough to realize what a piece of crap their product actually is.
