The Weyland-Yutani MK221 Tactical Shotgun was a self-loading semi-automatic shotgun used primarily by the United States Colonial Marine Corps.


Constructed of heat resistant alloys, allowing the weapon to maintain structural integrity after firing multiple shots in quick succession. The centerpiece of the weapon other than the automatic firing rate is the underbarrel arc launcher, firing arc rounds designed to deliver an electrically charged shotgun slug that paralyzes human enemies, killing Xenomorphs instantly.

Various customization options were available for the MK221, including ID16 Incendiary Shells, H34 Fragmentation Rounds, the R2 Recoil Dampening Stock, C47 Box Magazine System, S91 Dot Reflex Sight, L14 Laser Targeting System and Motorized Cycling System.