USAS-12

The USAS-12 is a non-canon, semi-automatic/full-auto shotgun featured in some fanon maps.

Blackstar27
The USAS-12 appears as semi-automatic shotgun in the Remember When... storyline in most maps and is availiable off of the wall. When pack-a-punched, it becomes the Y0ur F4c3 and it gains a grip and incendiary rounds.