Agreed, milspec isn't the least quality part on the market. In fact, one of the great unknowns in the AR parts world is what country of origin they come from. There are plants making AR's, and all the parts, across the world. There is no guarantee it's made in the USA - Brownell's attempts to flag all the US made parts, even so, it runs less than 50% in my casual perspective.
What lowers the price on the part may well be nothing to do with it's quality, however. One of those things is MPI - magnetic particle inspection. Basically the part is dusted and put in a magnetic field, it collects along cracks where the field is interrupted. That can show defects - it's an old technique used by machinists to inspect engine parts to prevent working on them when they are already defective.
The Army says they want every single bolt inspected - but the makers know they generally average a certain small percentage that will likely fail. Do they check every one? We take their word on it when it's marked, goes to buying the seller. But, a bolt that wasn't checked and marked isn't necessarily inferior - if the failure rate is, say, less than 1.5%, that's maybe one or two in a hundred. Under a mil contract they are culled, but looking again, that crack may be minimal and in an area that doesn't affect performance whatsoever, like, out on the tail of the bolt. Cracked lugs get scrapped.
So, the makers, already knowing they have a minimal defect rate, can and so skip the process because of the increased expense - and pass the savings on to the buyer. That bolt may be identical in all other respects. And, if it fails, it likely has a warranty because the makers don't like customers bad mouthing them. It hurts sales. It's just cheaper to hire someone in Customer Service than test every single bolt they make - much less all the other parts coming off the assembly line.
The TDP outlines all that for gov't purposes, but for civilian sales, the makers/assemblers have a price point to stick to. There are $1,500 AR's, and $650 AR's. To meet the lower sales price point, something has to give - and MPI inspection of every bolt is frequently targeted. Why? Because it's a government spec, and the makers only do it for contract guns. They don't MPI every bolt they sell in their other firearms, either. Again, it's expensive, and all those firing pins and slides in their critical defense handguns don't get it, either.
It's a internet chest thumping exercise in the AR world, nobody much else mentions it. And that is because the AR fan typically tries to find some reason to justify why his gun is better than everybody elses. It's oneupmanship, the locker room measuring contest. Actually being able to use it is RARELY discussed. Nobody talks about their latest ranking on the carbine at a match.
On gun forums, we talk a lot about guns, and parts, and the focus is on them. Not our skill or ability. So when it comes down to ordering the minions in their place, we tend to use the milspec TDP or whatever to rank the members. That's where we get into such spirited discussions - our ego is on the line. In reality, all the stuff that we insist be done with an AR would make the average handgun carried for self defense an expensive and inferior product.
