The receivers on the Armalite are made of 7075T6 aluminum, while the DPMS are made of 6061. Bushmaster/Remington do not specify which alloy they use in the .308 AR models but they do specify 7075 for the AR-15 (so does DPMS, BTW.) SO this leads me to believe that Bushmaster uses 6061 in their 308 ARs, unless somebody can point me to a Bushmaster link that says otherwise.
To me, that is a BIG differentiator, which is why my planned AR-10 build starts with Armalite receivers.
