I have been using a 4-14 PA R-Grid 2b on a 223 AR out to 600 yds, on a 6x45 AR out to 1000 yards and currently on a .243 Win AR10 out to 1000 yards (All in AR-Tactical). The 14x magnification seems to be plenty on the NRA targets used in AR-Tactical.-Budget? If on the lower end, you might check out either the 1-6 or 1-8 ACSS scopes from primary arms.
My son (Dylan) prefers the SWFA 10x on his .223 and competes with it out to 1000 yards. He currently holds the CMP Long Range AR-Tactical National Record with a 194-2x shot at Camp Perry last year.