Tau Cannon

"'Put that down, it's a prototype...'"

Background
The Tau Cannon, also known as the XVL1456, is an experimental energy weapon is in essence a  Gauss rifle, is a type of mass driver consisting of one or more coils used as electromagnets in the configuration of a linear motor that accelerate a ferromagnetic or conducting projectile to high velocity.

generally consist of one or more coils arranged along a barrel, so the path of the accelerating projectile lies along the central axis of the coils. The coils are switched on and off in a precisely timed sequence, causing the projectile to be accelerated quickly along the barrel via magnetic forces.

A prototype energy-based assault rifle, the Tau Cannon is a weapon its advanced technology allows it to use depleted Uranium-235 or Uranium-238 as ammunition.

Trivia
This weapon makes reference to one of the main guns of the franchise Half Life