Aaaaand we could mate 2 or more together and fire them using a cam system to actuate the triggers.
It would be akin to a Gatling Gun, and it would be awesome.
They did something like that on sons of guns some years back. They hooked the gas tubes from ARs to gas keys of bolts in a rotating pattern. Kinda hard for a pump gun, but we COULD take some DI automatic shotguns and do that