Pictured is a type of muzzle-loading improvised firearm sometimes encountered in Russia. The barrel usually consists of a length of steel or copper pipe, either capped off or hammered and folded shut at it’s breech end. A hole is drilled on top over which toy caps are placed and held by a strip of tape. It’s hammer consists of a bent length of metal bar attached to it’s handle which is allowed to snap down onto the toy caps with the aid of an elastic band or tension spring. Sometimes a trigger in the form of a simple hook is added, or more often the user simply pulls the hammer back and releases with their thumb.
Crushed up match heads are often used as improvised gunpowder with a lead projectile or ball bearings loaded in front. The basic mechanism is very reliable and the ignition area somewhat waterproof, offering an advantage over a basic matchlock design.