7.5×55mm Swiss

The 7.5×55mm Swiss or 7,5mm GP 11 (or unofficially 7.5×55mm Schmidt–Rubin) is a cartridge developed for the Swiss Army. It originated from the Gewehrpatrone 1890 (7.5×53.5mm) developed in 1898 by mechanical engineer Lt. Col. Eduard Rubin for rifles based on Rudolf Schmidt's action design. The 7.5×55mm Swiss GP 11 cartridge is similar in appearance to the slightly smaller 7.5×54mm French round though the two are not interchangeable. The Gewehrpatrone 1890 cartridge has been in Swiss Army service since 1889 in their Schmidt–Rubin Model 1889 rifles. The previous generation of the military calibres used in Europe at the time were 10 to 14 mm (and black powder) as opposed to 7.5 mm of the Schmidt–Rubin ammunition, but the transition was underway in late 1880s (e. g., 8×50mmR Lebel was adopted in 1886 and 7.65×53mm Mauser in 1889). It was one of the first with 7.5 mm copper-jacketed rounds similar to those used today. Originally using PC 88 ("powder composition-88") rauchschwacher ("low smoke" - equivalent to "smokeless") cut tubular smokeless single-base powder relying on nitrocellulose as its propellant ingredient, it was known as the Gewehrpatrone 1890. The Gewehrpatrone 1890 round was loaded with a paper-patched lead hollow based heeled steel-capped round-nose bullet. Starting from the rear of the nose section the bullets were wrapped around by two turns of paper, much like cotton patches were placed around the bullet of a musket. This paper patching reduced metallic fouling of the barrel and was supposed to aid in the gas seal of the bullet. It was discovered that the primer was far too corrosive, so it was updated in 1903 to the Gewehrpatrone 1890/03 cartridge. Long after the discontinuation of the Schmidt–Rubin Model 1889 rifle in the Swiss armed forces, the GP 90/03 cartridge was updated in 1923 and designated the Gewehrpatrone 1890/23 (officially abbreviated GP 90/23 after ca. 1961), for use in shooting competitions. The GP 90/23 was a 7.5×54.5mm round developed to be able to be used in arms chambered for Gewehrpatrone 1890 and GP 11 ammunition.