The Shotgun is one of the Weapons in The Final Station, an additional weapon to the Pistol.
The Shotgun is a double-barreled weapon, chambered in Shotgun Ammunition, holding 2 shells. When fired, pellets are shot in an a medium-spread from the barrel. This spread, and the large number of projectiles makes the Shotgun incredibly effective at crowd control at close range, yet ineffective at long range, where few pellets connect. The Shotgun, once acquired, becomes an alternative weapon that you can use, in addition to the Pistol, where you can switch either by pressing (Tab) or (1) and (2). Additionally, while the Shotgun is equipped, using melee will perform a kick and a strike with the butt of the Shotgun, as opposed to the standard punch, dealing slightly increased damage, (and potentially with a slight increase in range, although I have not been able to confirm this).
The Shotgun can be found in the upstairs armory of the railway office in New Costfield, and while it does not appear to be a mandatory weapon to acquire, it's ability to crowd-control with few shots proves useful almost immediately after. Following the acquisition of the Shotgun, Shotgun Ammo will sometimes be found in the environment, and Shotgun Ammo will become craftable on the train. Shotgun Ammo is significantly rarer, both in frequency, and in volume than Pistol Ammo.