The 7.5×55mm Swiss or GP 11 (or unofficially 7.5×55mm Schmidt–Rubin) is a cartridge developed for the Swiss Army by Lt. Col. Eduard Rubin for rifles based on Rudolf Schmidt's action design. The ammunition used by the Schmidt–Rubin Model 1889 rifle was one of the first to use 7.5 mm copper-jacketed rounds similar to those used today. The GP90 7.5×53.5mm round designed by Colonel Rubin was revolutionary in that the most popular military calibres used in Europe at the time were around 10 to 14 mm as opposed to 7.5 mm of the Schmidt–Rubin ammunition. Oddly enough the round was "paper patched" meaning the actual bullet was wrapped around by a piece of paper, much like cotton patches were placed around the bullet of a musket. Paper patching the round was supposed to aid in the gas seal of the bullet.