In my personal experience as a firearms instructor, dealer, and armorer. I have personally seen more Olympic Arms made AR-15s fail.
I've seen the gas tube to the front site base worked loose. Their staking on the bolt carrier keys are horrible. As in they don't stake their bolt carrier keys. I've tried many a time to mate a non-Oly upper on an Oly lower to find the mag well doesn't line up properly. Non-Heat Shielded Hand Guards,
Olympic Arms level of quality is not near that of DPMS, Colt, S&W, Bushmaster, Rock River, Saber Defense, FH Herstal, Noveske Rifleworks, Armalite, CMMG and many other name brand AR-15s.
90% of the AR makers have the same level of quality because they subcontract for everything. Lowers Receivers, Uppers, Barrels, trigger components, etc.... Colt, the supposed name of Quality even subcontracts. Olympic Arms does not.
Right now the Big two sellers are Bushmaster and DPMS. There are more Bushmasters sold then any other brand of AR-15. Bushmaster, DPMS, Remington, Marlin, New England Firearms, and Harrington and Richardson (H&R) are all owned by the same parent company.
Remington's .223 AR-15 is a Bushmaster Predator Series with a Remington V-15 Roll Mark and their .308 AR-10 is a DPMS LR-308 series with a Remington V-25 Roll Mark.
DPMS sells high quality rifles around the $700 price range. You can get a well built Bushmaster for the $950 price range.
S&W doesn't even make their own rifles. They subcontract....
Will a Olympic Arms rifle work? Yes. But will it be the same level of quality as the others? No.
Hell, Century Arms is selling A2 Configuration AR-15s around the $550-$650 price range. They use a new lower with surplus Colt/FN Uppers.
The main builder of parts are the following. CMT/Stag, MEGA, Superior, AMEETEC, Rock River, Noveske, Lauer, LAR, and Double Star.
CMT owns Stag. CMT also makes Rock River, S&W, and some Colt receivers.
DPMS doesn't make their own receivers. They are made by LAR. (which most people didn't know made AR recievers, but they are actually one of the highest producing AR manufacturers there is).
Hence why I recommend the following companies.
DPMS, Colt, S&W, Bushmaster, Rock River, Saber Defense, Noveske Rifleworks, Armalite, Stag, and CMMG
Properly Staked Gas Key (Colt Firearms MFG)
Non Properly Staked Gas Key (Olympic Arms)
That is one of the major issues of a rifle that does not properly work.
Olympic Arms is known about it.