A few doodles on the shotgun barrel appear to depict stalkers killed with the weapon.In-game description
The bandit's Chaser 13 is identical in appearance to a regular Chaser 13, the only difference being that it cannot be traded (as it is a quest item).
The weapon is part of a quest provided by Bandits squad leader in the Garbage. The weapon must be retrieved from the body of a deceased Bandit that died after forcing a digger to walk through an anomaly field. The body can be found in the middle of a radioactive anomaly field full of whirligigs near the southern path to the Dark Valley, so caution must be taken when the player attempts to retrieve the shotgun.