OK, so here's what I found from my research over a year of looking to buy. DPMS was the "other" go-to for .308 rifles in the AR style. Armalite made the AR-10. DPMS made a clone. The visible difference is in the mating surface at the rear of the receiver. The Armalite has a slant cut of about 45 degrees at the buffer tube. DPMS on the other hand replicated the AR-15 pattern of a rounded mating surface at the buffer tube. I know Diamondback is an Armalite style. Most of the other producers followed the DPMS model. BUT- and this is key! THERE IS NO MILSPEC STANDARD IN .308 AR TYPE RIFLES!!! You can buy separate uppers and lowers, but you must insure they will mate, otherwise you waste your money. You can go to 308ar.com and there are some pretty good explanations over there. Some of the folks are abrasive, but a very good bunch overall and build a lot of their own stuff. The Springfield Armory Saint Victor .308 seems to be really hot right now. PSA has some issues, BUT they have a lifetime warranty and they are not shy about talking you through or fixing your product. DPMS and Bushmaster were bought out by Remington, who were then bought out by the Freedom Group, backed by apparent anti-gun investment companies. After building an entire new plant in Huntsville, AL and employing 2500 people they closed the plant and put DPMS, Bushmaster and TAPCO all out of business in April of this year without warning. So the lifetime warranty means nothing. I almost bought an Oracle but walked away. I ended up finding a new in the box AlexPro Firearms Armory in .308 for $800. AlexPro took up where DPMS left off when that company left Minnesota. Smoky Mountain Guns and Ammo had them, but are probably gone...Waiting on some match ammo to get her out and see how good a purchase I made . Armalite is recognized as the leader in .308 gas guns, they just run and you can fund a basic model for around $1100. The market just doesn't have as much support for accessories for the Armalite platform. Hope this help, YMMV...