Gear-Ratio-Accelerated? Yep, It's a Thing: French MAT 1955 Prototype
14m
EDIT: Shoot, I managed to get the gear ratio backwards. Sorry! The recoil action provides the necessary delay, and then the gear ratio provides acceleration to ensure the bolt can open reliably, akin to the accelerator in a Browning M1917 or 1919 machine gun, or a Lahti L35 pistol. Please excuse the error...
In the search for an improvement to the MAS 1949 rifle for the French military, all the French arsenals proposed new designs. MAS supplied an updated version that was ultimately adopted as the MAS 49/56, but the Tulle Arsenal (MAT) had a wacky idea of its own. In 1955, they presented a short-recoil, tilting bolt, gear-ratio-delayed system. It was an open bolt firing rifle chambered for the 7.5x54mm cartridge, using detachable 20-round magazines. Today we have one of the first models to look at, and there was a second iteration in 1956, which lightened the rifle by replacing some steel parts with aluminum. Neither was successful, much the the relief of the French Army...
Many thanks to the IRCGN (Institut de Recherche Criminelle de la Gendarmerie Nationale) for allowing me access to film this unique rifle for you!