Aero Precision, you buy a complete upper from them, you pick, then you pick your complete lower set up. you can get a kick ass rifle for 1000 easy. my fir rifle was from Aero, and is my go to rifle every time. took a wild pig at 60 yards from a boat. 20 yards from the shore she was another 40 beyond the shore line and behind two tree side by side with 6 inches between them. its a dead on rifle. most people will tell you these fancy rifles that sound cool look tactical but are a failure as a proper gun. like the guys with 4 flashlights, side optics scopes for 1000 yards on a gun built for 3oo yrd shots.
Bushmaster XM-15 M4A3 it goes for around $810. It's nothing fancy just your basic AR-15. I will tell you that it is lightweight, comes with 16 inch barrel, adjustable stock, the carry handle, it also comes with mangabese phosphate (parkersized) external finish and a chrome lined barrel for rust protection. Super easy to clean. The aluminum is anodized for protection from rough handling and corrosion. You can also check out the other options as well but this is what comes in my mind when it comes to AR-15's under $1,200.
Your best bet is going to be Savage Arms MSR 15 Patrol. The reason I say this is because it was designed for precision shooter.
This rifle features .223 Wylde chamber which can shoot .223 or 5.56 ammo with increased accuracy. The barrel wis treated wutg nelonite which is one of the most and durable high tech finishes available today.
The power of this rifle comes from a mid-length gas system. Which cuts down the recoil and provides smoother action with less wear on parts. It also includes single stage trigger and Blackhawk furniture.
Only bummer thing about this product is that it doesn't have many accessory mounting options as other rifles in the same price range.
First, none of these guns are AR, they are DPMS variants. Second 223 wylde is not the answer for your ammo caliber. Its a fine barrel fir shooting what ever you get your hands on. However 556 barrel have alwats been able to shoot either 223 or 556. Wylde is more a marketing stunt. Anything savage is a good product out of the box.