"The Collector Shotgun, based on the Collector weapons featured in Mass Effect 2 and 3.

Modified by Cerberus scientists from weapons recovered at the Horizon attack site, the Collector Shotgun fires impact reactive rounds, allowing it to bypass a target's armor and deal direct damage. A bayonet attachment has been included with this version to improve melee attacks on close-range opponents.

Thingiverse: https://www.thingiverse.com/thing:6038419"