Both Piratez and X-Com Files have this exact type of laser shotgun, too. And variations, like plasma, sonic or chemical rounds.
If you want actual battery-powered weapons, i.e. variable-charge shots, these also
exist. Not sure to what extent they are incorporated into the big mods. Edit: Couldn't find anything, so it's probably a more niche thing. Maybe in 40K? /edit.
There is also the option to mount different types of ammo at the same time. An interesting example is the 'Human Sonic Shotgun' in XCF.
All in all, a read through of the big mods' weapon list (and possibly associated scripts, too) is a good way to broaden your knowledge of what's already possible and what kind of tricks people have come up with.