One of the most mechanically unusual rifles I have had the chance to examine is the SIG AK-53. One of a long line of interested experimental self-loading designs made by SIG between the 1920s and 1950s, the AK53 is a gas operated rifle with a fixed breechblock and a barrel that cycles forward when fired. The gas system compresses a spring rearward first, which then releases and pushes the barrel forward in a system with a few elements in common with the British Farquhar-Hill rifles and machine guns. The magazine is also unique in design to allow rounds to move directly upward so as to have the barrel drop over them in a reverse sort of feeding (the magazine bears some vague similarity to the Madsen and Mendoza LMG magazines in this way…a bit). For reasons which will become very clear upon disassembly (if not already made clear by that description), only prototypes of the rifle were ever made, with no series production.
Many thanks to the Royal Armouries for allowing me to film and disassemble this very rare rifle! The NFC collection there – perhaps the best military small arms collection in Western Europe – is available by appointment to researchers. Anyone, however, can browse the various Armouries collections online here.