True that there are just a few companies that actually manufacture parts for AR's. So in a lot of cases we are not even arguing Ford vs Chevy, we are arguing Chevy vs. GMC. Same thing.....different sticker.
Over the last 15 years or so, I've built, rebuilt, reconfigured and re-purposed a crap ton of AR's and used components from just about everyone in the game. As far as small parts go, the PSA premium stuff I've seen is right along the same line of quality as DD and BCM. I've got DD and PSA LPK's at home right now and you really can't tell the difference between the two. As far as failures go, I must be some sort of exception, as far as I can remember, I've never managed to break anything on an AR and I shoot them a little. The oldest rifle in my cage has a Bushmaster lower and BCG with a DPMS High Rider upper receiver. This thing is on it's third (soon to be forth) barrel and I can't even imagine how many rounds it has through it. If I were to fathom, it would be somewhere around 20K. Never so much as replaced an extractor spring on it. This is on a varmint/target rifle so if it goes down, no big deal. If I were to use this as a primary defensive rifle I would probably elect to do some more preventative maintenance, but for now she just keeps chugging along.
IMHO, what you are buying as far as QC is concerned with what are regarded as the upper tier manufacturers (I'm going to exclude Colt here) is a step up in how the rifle is assembled and inspected once complete. They actually might give a ****, where the PSA, DPMS, Bushmaster, Colt (gasp!) and the like rifles, often seem to be assembled by employees that care more about punching a clock than they do about creating a fine rifle. A lot of "Meh, good enough" attitude would be my assertion from what I've seen.
As far as DPMS using the commercial buffer tubes.....I can only ask why?.........why does anyone use these things? Can we all just use the same parts please? For the staking on the gas key......do not pass go, do not collect $200. Gas keys coming loose is one of the most common issues I've seen that make single shot AR's.
As far as the DPMS Oracle is concerned........yea. It's a $600 out the door rifle, built to appease to the masses, that most likely won't put more than a few hundred rounds through it in it's entire life, and for that, it works......it's not gonna be the cream de la crem. Could one build a much nicer rifle with better components for the same money.....yep.
Back to the PSA debate. While the premium stuff is pretty good, but the PTAC/Freedom line is not even in the same ballpark. I recently ordered a complete rifle kit from them. This was actually the first time I'd ever bought a complete rifle kit (minus lower receiver). The reason here is I really wanted to try out the new Vortex Spitfire 1X optic and they had a deal where for $500 you got the rifle kit with the optic. This was like getting the optic for free or a complete AR for like $350. A win either way. The parts in that kit were noticeably crappy in comparison to the regular PSA parts and I'm guessing were probably imported from the ROC. It works though, ran 10 rounds through it for function test and now it will sit in the safe until the next panic and I'll send it down the road.
All that said, I look forward to further installments.