An automatic, 12 gauge military shotgun. The best weapon for close quarters, except for a Flamethrower.
A fully automatic shotgun that does decent damage but loses it's effectiveness at later levels.
This shotgun can be located in the town of Quincy's detention center, inside one of the prison cells in a chest.
It can also be found in random encounters while travelling the Wasteland directly around Bunker Alpha once the Brahmin Wood mission has been completed. Ghost-like "citizen-thin" NPCs often carry one each (along with a stimpak and some 12 gauge shells). If you can't see it in the initial steal inventory window, let one of your team members get caught stealing from that NPC; on the next turn when you enter the Steal window, it will be there. You need about 80% Steal skill to be able to grab the weapon. If the NPCs wander around a lot, enter turn-based mode by pressing Enter.
In real life, the Neostead is NOT an automatic shotgun, it's a pump-action shotgun with a "forward-back" handguard movement instead of the classic "back-forward". Its main distinguishing feature is a unique double magazine, allowing the shooter to immediately switch between two different types of ammunition (i.e. non-lethal shells for riot control, with lethal rounds held in reserve for emergencies). It was developed by two South African engineers, Tony Neophytou and Wilmore Stead, in the early 1990s.