Recoilless and Full-Auto Shotgun

The Auto Assault-12 (AA-12) is an automatic 12-gauge shotgun that can fire 300rd per minute and is nearly recoilless, 300rd for a auto shotgun is too many in a minute.
Basically, it’s incredibly powerful and you really don’t want to be fighting with an enemy who has this weapon at close range, even in games.
It’s also claimed that it requires no cleaning or lubrication ever, I’m not really sure how that would work, in any case, you don’t really care, what you care about is that it’s a big gun and makes loud noises and blows shit up like you never seen before.