This animation shows the firing mechanism for the Christophe-Montigny mitrailleuse (grapeshot shooter) developed around 1863 in Belgium. The model shown here has 37 barrels, and is quoted as being able to fire 6-8 salvos (nearly 300 rounds) a minute, although the cartridge mounting plate looks to be a weak design. This gun was adopted by Austria in 1869, and although tested by the English, was rejected in preference to the Gatling gun. For more information on the Montigny mitrailleuse, including a description of the operating mechanism, Google search for Victorian Ship Models, or anti torpedo boat guns.