All you need to bump an AR is a light trigger, sand bag type rest & light hold on the rifle.
Set the rifle on the bag, set stock against your shoulder, hold the rear of the stock up with left hand, look through the sight and put it on target, rest the right hand trigger finger on the trigger, don't hold the grip, and slowly pull the rifle forward with left hand keeping the trigger finger in one place.
With a little practice you will be able to hold on target at a reasonable distance, bump and still hit the target.