Shotguns as assault weapons?
Most likely mag-fed shotguns. I think they actually listed any gun “capable” of receiving high-cap mags, which is literally any mag-fed gun, including handguns.
YUP; just ask the Krauts in the trenches of WW-1.
When the US Marines used the Model 1897 WINCHESTER shotgun to great effect.
Invented by JOHN MOSES BROWNING, prior to World War One it saw action in the Philippine and against Pancho Villa.