I own several and am generally pleased. My latest is this .308 upper: https://www.bearcreekarsenal.com/308-22-bn-light-weight-barrel-1-10-twist-rifle-15-mlok-forged-upper.html
I'm still finishing it. But so far, so good. Picture below. Just waiting on a buffer tube.
According to BCA's FAQ: What platform pattern are your AR10 Uppers?
Our uppers are made based on the DPMS Gen1 Low Profile model. With the AR10, there are many different designs and models out there, and each company tends to create and design its own unique platform. For that reason, we cannot guarantee the fitment of our uppers to any other companies lower other than our own.
AR10 are their words; not mine. Thanks to this forum, I now know the difference.
Any way, according to me: BCA's prices are hard to beat but :
Most of their barrels are heavy
Most of their barrels are parkerized
Part of their strategy to keep prices down is that they (usually) don't do any machining they don't have to. Owning and operating CNC machinery is expensive.
Let me know if there is anything else I can share about my BCA experiences.
Mark