A Barrett 82A1 really isn't so bad. I have shot nearly 200 rounds out of it in a day without too much discomfort which is more than I can say for a stock 870 shooting skeet. I have shot a couple bolt action .50 bmgs that even with the muzzle brakes were a bit of a kick in the pants that started in the shoulder.
As in the old Super Chicken cartoons where Super Chicken was always just off center from the explosion and got blasted but the lion sidekick at the center of the explosion was unharmed, being directly behind the rifle is the quietest place to be, most peaceful as well. You don't want to be a spotter 3 feet to the side of the shooter with a .50 BMG and proper muzzle brake. It is not a pleasant place to be.
"If you look through your scope and see your shoe, aim higher."
-- said to me by my 11 year old daughter before going out for hogs 8/13/2011