I bought my first AR a few months ago, being a big bore kind of guy, it just had to be an AR-10.
I haven't had the chance to shoot it a lot, but the ammo is purchased,
(Black Hills .308 Win Match), and plan to get busy with it this summer.
The is a DPMS LR-308B, flat top, 18 in. bull barrell, with 3X to 9x Bushnell Scope. First time to the range I had only one box of ammo on hand. At 50 yards, using a freshly mounted, unsighted scope, the first round was about 5 inches high and 1 inch to the right. Clicked it down a few, and the second round was 1 inch to the right, and about 2.5 inches high. Moved out to 1 hundred yards, and tweaked it to 1 inch high, and centered.
I was shooting from a bench, with no other support, so I couldn't do much more. Next trip, I'll be using a Lead Sled, and shooting at two hundred. If I can get acceptable groups there, I'll follow up with a trip to the 6 hundred yard range, (soon to open in Oscoda).
I guess I'm pretty happy with the DPMS.