Abstract: A firearm mechanism, especially for automatic or semi-automatic shotguns, with a covering upwardly closed breech-block housing consisting of two mutually fitting and fixedly attached parts, an outer casing part made from sheet by pressing and a precision-cast inner part, which is stiffening the outer part and is provided with guiding surfaces for movable parts in the mechanism, e.g. a breech-block. The outer part is stiffened also by a lower mounting, closing the housing and having upstanding walls projecting in the housing. Cartridge feeding catches are arranged in the lower mounting, attached to its upstanding side walls.

Abstract: A shell cut-off latch for use in a break-open firearm having a magazine tube mounted parallel to the firearm barrel. The cut-off latch functions to retain cartridge(s) in the magazine tube when the firearm is in the break-open position and is cammed out of latching position when the firearm is in closed position and the action assembly and bolt means are in the forward, ready-to-fire position.

Abstract: A safety device for guns such as gas operated shotguns having interchangeable barrels. The barrels may be chambered for different-sized cartridges or shells, such as 23/4 inch shells or 3 inch shells. It would be unsafe to load a 3 inch shell into a barrel chambered for 23/4 inch shells. The invention is a safety block or lug which is fitted to the barrel chambered for the smaller size cartridge, the block having a position such that it is not possible to load the larger size cartridge into the gun.

Abstract: A support member positioned between a receiver assembly and the rear end of a removable barrel assembly having "C" sections on each side of the support member to support the rear end of the fore-end and also to permit sliding movement of an action bar assembly therein. At the rear of the support member is a spring section which is positioned between the receiver assembly and the barrel assembly to compensate for variations of tolerances between the barrel assembly and the receiver assembly.