The PTRS (ПТРС - ПротивоТанковое Ружье Симонова- Simonov anti-tank rifle) was rapidly developed by famous Russian arms designer Simonov during the late summer of 1941, when Red Army issued the urgent requirements for a man-portable and inexpensive anti-tank weapon, suitable for infantry use. Developed, produced and used concurrently with Degtyarov PTRD anti-tank rifle, it became an important asset of the Soviet infantry during the earlier stages of the Great Patriotic war, altought the PTRS was manufactured in smaller numbers, due to its more cokplex and expensive construction. This weapon used a powerful round, especially designed for anti-tank role, which fired armor-piercing projectiles of 14.5mm caliber (see 14.5x114 entry in Ammunition section for details). With improved BS-41 armor-piercing bullets with tungsten cores the PTRS was able to penetrate of up to 40 mm of steel armor at 100 meters range. The same bullet also easily penetrated log and sand entrenchments, brick walls and other battlefield obstacles, to provide fire support for infantry. About 60 000 of these rifles were manufactured in USSR in 1941 and 1942, when rapid evolution of German armor made these anti-tank rifles obsolete. Nevertheless, many PTRS rifles were used as ancillary anti-tank and infantry support equipment until the end of the war, and few also saw the action during the war in Korea. The Simonov PTRS anti-tank rifle is a semi-automatic weapon that uses gas-operated action. Short-stroke gas piston is located above the barrel, and the barrel locking is achieved by vertically tilting bolt. Gas block is fitted with manual gas regulator with 3 settings. Feed is from integral box magazine which holds five rounds in en-block clip, similar to that used in US M1 Garand rifle. Clips are loaded into integral magazine from the bottom, by unlatching the magazine body, swinging it down and forward, loading the clip into the body and then closing and locking it back to rifle. Magazine is fitted with automatic bolt stop device, which locks the bolt group in the open position once tha last cartridge is expended from magazine. To mitigate heavy recoil, Simonov PTRS anti-tank rifle is equipped with massive muzzle brake and rubber buttpad. Iron sights are adjustable for range between 100 and 1500 meters in 50-meter increments, although the rifle was considered to be effective only up to 300-400 meters.Simonov PTRS anti-tank rifle is also equipped with folding bipod and a carrying handle.