The Mark-4 version of the Modulator rifle, manufactured by the Volt Energy Weapons Corporation. It fires a green blast of plasma, fed into the weapon via battery packs that allow a sustained blast of energy for a total of up to 30 seconds before fully draining. 

Highly customizable, the user can adjust various components of the weapon to fit their operational needs. As depicted here, we see the Sphinx 1-3x24 variable optic scope for short- to medium-range engagements (with a space allowance underneath for holograph-assisted backup ironsights); along with an aftermarket onboard computer, which displays info about the weapon’s current status.

Another energy gun - this one, of course, is mostly inspired by the design of an M4 / AR-15 platform rifle, with a bit of inspiration from the H&K UMP as well. Something that’d been seen by U.S. infantrymen, but in some far-off, really “out there” alternate future.