The Manville is one heck of an angry looking gun. If you've seen the Christopher Walken classic, Dogs of War, you've seen this gun's cousin. But in the 1930s a machinist had an idea for a large capacity gas gun for use by police during riots.
The Manville essentially is a large revolver, that was born in 1936 as a 12 gauge riot gun. designed to arm police and prion guards in riot situations, the Manville gas gun was an intimidating looking and performing weapon. The first generation of the Manville was chambered in 12 gauge and carried 24 rounds in a cylinder.
Generation two came along, rechambered in 25 mm and bearing 14 rounds. To move both hefty cylinders, a clockwork spring assisted the revolver-style action. And each chambered round sat in front of a receiver pan holding an individual firing pin, as measure against jams or breakages.
Ammunition for the 12 gauge and 25 mm Manville's were several types of less-than-lethal gas. Loading the beast was not a quick procedure. Two knurled knobs atop the receiver were undogged, releasing the barrel and front cylinder assembler. Each round, whether 12 gauge or 25 mm was individually placed into the cylinder. Importanly, normal 12 guage rounds would not work in the standard gas gun due to the construction of the cylinder and its ability to handle the associated pressures.
A simple safety on the rear of the gun as a spring tensioned knob that was pulled rearward and twisted, ensuring the gun was on safe.
Eventually as war enshrouded the world in the 1940s, Manville tried enlarging the gun once more, this time as 37 mm. Unlike its first two generations, this third 37mm dispensed with less-than-lethal and became an unsuccessful anti-armor grenade launcher.