What are the qualitative differences? if it shoots, runs and lasts, how is quality measured?
Americans love to spend money on gadgets, "new" is the flavor of the week- does not matter what it is- cars, tools, guns, ski's, hairstyle, software, there is always a new gadget to separate "consumer" from money. So the question is, it something better, in any measurable sense, or is it just new?
Well "shoots, runs, and lasts" is kinda the qualitative difference in my experience. A PSA gun will often have cheaper small parts. Things like extractor springs, extractor buffers and buffer springs will often have a distinctly shorter life. I've seen gas blocks with no dimpling of the barrel under them, or not great gas port alignment. Barrels can be a mixed bag, Some of PSA's barrels are FN CHF barrels, and those are great. They had a "freedom line" I think it was called for a while that seemed to be the shittiest AR barrels I've ever seen. I saw keyholeing on brand new guns. The cheaper builds are often closer to the edge of running reliably and will act up when dirty, too cold, or too hot, where a more carefully built gun won't. Cheaper builds are often over gassed to combat these issues, which then leads to more gas in the face, more fouling, and a harsher recoil impulse. If you are trying for quick follow up shots, or keeping the target in the scope to spot your hit, 30% difference in buffer velocity when it bottoms out is pretty noticeable. Then there's your definition of "Run" If a PSA has 500 MRBF and a Daniel Defense has 6000MRBF, that's a huge qualitative difference, but may not be noticed by a casual shooter.
So the better builds, IME, shoot better, run better, and last longer than a PSA (or Core15, or Anderson, or whatever the budget build of the day is). It is very possible that any one person's use case for an AR-15 will be filled just fine by the not as good performance of a less quality build. That's up to the person.
I want to be clear: There's a place for budget AR's. I own several. If I want some weird caliber or configuration to play with as a range toy, I might not want to sink $1500 into it. Or an upper for a 3D printed lower. I run a PSA there. Someone that wants their first MSR and plans for less than 500 rds a year just to practice? Sure, get you a PSA and rock on. I only mentioned the difference because we brought PSA into a conversation of over $1k AR's, and they're not really the same creature. Caveat: If you go budget enough to run up against Century style builds, spend more money.
Pb: I've never played with an full Aero build, but I run Aero recivers in my AR-10, have a freefloat rail of theirs, and a couple of their scope mounts, and everything I've ever gotten from them was really nice stuff.
