It's a pump-action 12-gauge shotgun with extremely high stopping power, capable of taking the player or an enemy down in a single shot. The weapon is preferred by gangsters as well as police officers, who will use it against the player once their wanted level reaches 3 stars.
The weapon can hold 8 shells and the player can carry an additional 48, for a total of 56 rounds. The shotgun's slow rate of fire is made up for with its high power, but it's very time-consuming to reload. It occupies a slot in the bottom of the weapons HUD along with other non-automatic two handed weapons.
They become available for sale at Harry's Gun Shop in Chapter 5, you can purchase one when you go to pick up the MG-42. They're also used by some of Siney Pen's men later in the same chapter. They don't become available at McClusky & Son until Chapter 7.
In both The Betrayal of Jimmy and Jimmy's Vendetta, you start off the game with a shotgun in your inventory. In Joe's Adventures they are available for purchase from the beginning of the DLC from Harry's shop or McClusky & Son.
You can find more real world information about shotguns on Wikipedia.
- While not available until Chapter 5, you can obtain one as early as Chapter 2 by the killing the attendant at any McClusky & Son's store; however, the only way to get more ammo before Chapter 5 is to kill him again. They are also occasionally carried by police officers, and one can be found in the back room of The Lone Star bar in Chapter 2.
- If you reload and shoot the shotgun at the same time you can get an increased reload speed. Depending on how fast you tap the reload button, it will reload in under a second.