Alright, so I was watching Starship Troopers, and Rico is going into this bug planet hellhole with his assault rifle, leading his squad, when they get set upon, he ends up on his back and changes a setting on his assault rifle. Suddenly, he's firing it like a shotgun.

I just think that would be an amazingly versatile weapon, and I'm surprised it hasn't been done, have you heard of anything like that, is it even possible?

The only thing I can think of that's comparable is how the Gauss Rifle lets you fire normally or hold the trigger to 'charge' the shot, maybe that mechanic could be applied to a rifle, where you hold the trigger to get a shotgun blast.