This guy came to my club's range with an AR-50 type rifle. Had a muzzle brake along w/ the usual shock absorbing features on the frame. It was mounted on a bipod and sitting on a shooting bench; when it fired, the pea gravel around the bench moved like a wave.
He was setting it up for competition and let me shoot it. I shot at a target at 200 yds (short distance for this baby) and hit within 1/2" of dead center - it was better than he was doing. He gave me the target and the case which I still have.
I have no desire to get one of those bad boys - way too expensive for me and I'm not a target shooter. But it was pretty cool...
Mike