Solothurn S-18/1000
The Solothurn S18-1000 20 mm was a Swiss anti-tank rifle used during the Second World War. It was a variant of the earlier S-18/100 with modifications for a higher muzzle velocity, as well as a larger cartridge size. The more powerful ammunition resulted in significant recoil, which was problematic for the gunner, and its size made portability difficult. History. The Solothurn firearms company was owned by the German firm Rheinmetall, who used the Swiss company to manufacture arms which were prohibited for manufacture by any German firm under arms limitations imposed at the end of the  First World War. In 1940–1941 the US Army considered adopting the Solothurn S18-1000. The weapon was standardized for limited procurement as "20mm automatic gun T3". In spring 1941 the Solothurn was tested against the Colt .90-cal. (23mm) T4 automatic gun, an aircraft gun. Although not as powerful, the Solothurn was less bulky and complicated and was found more suitable for army use. The plans were to acquire 50 pieces, and later to produce the weapon in the US. However, long contract negotiations resulted in abandonment of the purchase. It was adopted by the Royal Italian Army  in 1940, when a first batch was bought from Switzerland; initially known as Carabina "S" ("S carbine"), from 1942 it was designated as Fucile anticarro "S" ("S anti-tank rifle"); employed primarily on vehicles given its size and weight, it was largely employed in North Africa; after the 8 September 1943 it was also used by the National Republican Army of the Italian Social Republic. The brakes are changed depending on the recoil force of the rounds being fired. Lighter projectiles require less recoil reduction from the brake to allow the action to cycle. Therefore, the one-hole brake is  used for firing high-explosive projectiles, which are much lighter than the armour-piercing variety. The AP projectiles require the 5-hole brake.