Have you ever spent time behind a sub-gun full auto? You're lucky to get the first couple rounds on target unless you've spent a LOT of time controlling it. We did an experiment one time with a M500 (000buck), MP5, M16A2, and M249. Each weapon was fired wide open at a target 50' away. At the end we counted the rounds on target. The shotgun had most on and the rest had a handful. These were guys who know how to shoot them. That's why most are regulated to three round bursts.