The condition exists because of the stiff spring inherent of the design. The primary contributing factor of the Sten magazine’s functioning problems is the feed lips’ propensity to spread apart when loaded, changing the critical feed angle of the top cartridge. Many of the earlier magazines were upgraded when processed through a British Factory Thorough Repair program (FTR). The new magazines were designated as the Mk2 design. The floor plate was held in place by a protrusion on a plate attached to the bottom of the magazine spring.Įarly Sten magazines proved problematic and were redesigned by eliminating the holes in the rear of the magazine (used to determine how many rounds were in the magazine) and adding a cross brace to connect the legs of the follower to keep them from spreading apart and dragging on the magazine body. The floor plate was made of sheet metal and bent to slide onto the rails formed on the bottom of the magazine body. A thick steel collar was spot welded to the top of the magazine’s body to form the feed lips. The magazines were fabricated from sheet metal, with the manufacturing process of the body varying slightly by manufacturer. Sten magazines were produced by a large number of contractors and subcontractors. The double-stack double-feed design, as was used in the Thompson submachine gun, is far more reliable and much easier to load by hand. The spring makes the single feed magazine difficult to load by hand, requiring the use of a loading tool, and places a lot of force on the magazine feed lips. The double-stack single-feed magazine design is a configuration that requires a strong spring in order to force the cartridges into a single row at the top. A similar magazine, in a 32-round configuration, was adopted for the British Sten submachine gun for the same reason. The German’s MP28II magazine was the same basic configuration later used for their MP38-MP40 magazines. The existing German magazine and the submachine gun were copied instead of designing a new one to save precious time. The reason for choosing that particular weapon was the manufacturing drawings had been made earlier from two weapons that were in British hands. The British Lanchester submachine gun and its magazine were a close copy of the German MP28 II submachine gun.
With such a proliferation of Sten magazines one has to wonder just why anyone would choose to make new ones.ĭuring 1940, the British were in dire need of small arms. Because of their availability and low price, Sten magazines have been adopted for use in a number of modern firearms, both as issued and in modified form. Today, Sten magazines are very easy to find on the surplus market and usually very inexpensive. During World War II there were an estimated forty-two million magazines produced for the British Sten submachine gun.