If you read the Questions and Answers it states that a BCG from a standard AR10 will not work in this gun. The upper receiver and BCG are a different diameter than standard. I like to keep all my guns standard size to uncomplicate things in a bad situation.
Therein lies the rub. There's no such thing as a "standard" AR-10. Since it wasn't adopted by the military (originally), there is no "milspec", and there's a mishmash of proprietary "standards". Most fall roughly into "Armalite" and "DPMS/SR25". Not even the magazines are interchangeable. Then even within the standards, there are quirks and exceptions. Then there's just crazy stuff. I
have had a DPMS *BRAND* rifle that's not even DPMS pattern, but takes SR25 magazines.
It's all confusing enough that I've elected to never build one myself. Of course most of the stuff you want to swap is generic. Stock, grip, trigger groups, etc. DPMS magazines, which the PSA rifles take, are far more widely available.