User blog comment:TheEvilThing/WEAPONS MASS EFFECT NEEDS AND LOGIC TO SUPPORT IT/@comment-1900300-20120221023817

Automatic shotguns are not widely used in the US military. It is more susceptable to damage, jamming and failure and is thus not as reliable as normal shotguns.

And in ME, shotguns opperate differently then todays shotguns. While todays shotguns fire a cartrage of pellets, in ME shotguns use mass effect tech to fire multipul slivers of metal at high speeds. Maybe in the ME universe they havent developed suitable atuomatic shotguns with this technology, since they have the differing limition of the gun overheating. Also in the ME universe, the extremely high speeds of the mass effect fired slivers mean combat is much more long range rather then short range as the slivers fly further. Sure there is still short range combat but the prefelence has lessened.