At 1000 yards the 5.56mm round has about 180 ft/lbs of energy left, approximately that of a rock thrown by a girl. It also drops over 300 inches at that distance, or 25 FEET. Add in any crosswind at all and you’re talking blind luck at hitting anything.
How ‘bout a 62 grain bullet, fired from an HBAR with 1:7/1:8 twist? C’mon Lurker, a girl can put your eye out with a rock from 25 feet.