The SKS () is a semi-automatic carbine designed by Soviet small arms designer Sergei Gavrilovich Simonov in the 1940s.
The SKS was first produced in the Soviet Union but was later widely exported and manufactured by various nations. Its distinguishing characteristics include a permanently attached folding bayonet and a hinged, fixed magazine. As the SKS lacked select-fire capability and its magazine was limited to ten rounds, it was rendered obsolete in the Eastern Bloc by the introduction of the AK-47 series of rifles in the 1950s. Nevertheless, SKS carbines continued to see service with the Soviet Border Troops and second-line and reserve army units for decades.
The SKS was manufactured at Tula Arsenal from 1949 to 1958, and at the Izhevsk Arsenal from 1953 to 1954. Altogether, the Soviet Union produced 2.7 million SKS carbines. Throughout the Cold War, millions of additional SKS carbines and their derivatives were also manufactured under license in the People's Republic of China, as well as a number of countries allied with the Eastern Bloc. The SKS was exported in vast quantities and found favour with insurgent forces around the world as a utilitarian weapon which was adequate for guerrilla warfare despite its limitations.
Beginning in 1988, millions have also been sold on the civilian market in Canada and the United States, where they remain popular as hunting and sporting rifles.
Design
The SKS is a gas-operated carbine with a conventional wooden stock and a fixed ten-round box magazine enclosed inside the receiver. It has a tilting bolt and a gas piston operating rod that works to unlock and cycle the action via gas pressure. When a round is discharged, some of the gases in the bore are diverted through the gas port and impinge on the head of the piston. The piston is driven rearwards and the tappet strikes the bolt carrier; a spring returns the tappet and piston to their forward position. The bolt carrier is driven rearwards, which causes it to lift and unlock the bolt and allowing it to be carried rearwards against the recoil spring. This allows the fired cartridge case to be ejected, and as the bolt is returned to its original position by the recoil spring it strips a new round from the magazine and chambers it.
The SKS magazine can be loaded either by hand or from a stripper clip which seats in the bolt carrier. To load the rifle, the cocking handle on the right of the bolt is retracted, and if the magazine is empty the bolt will remain at the rear. When the magazine is fully loaded, the bolt is pulled slightly back then released, at which time it will chamber the first round. Cartridges stored in the magazine can be removed by pulling back on a latch located forward of the trigger guard (thus opening the "floor" of the magazine and allowing the rounds to fall out).
When the magazine is expended, a small stud extension on the magazine follower engages the bolt hold open, locking the bolt to the rear. After the magazine follower is depressed by the insertion of ammunition or opened from the bottom, the stud continues to hold the bolt at the rear of the receiver until the bolt is pulled back, at which time it drops into its normal position and releases the bolt to chamber the next round.
While early (1949–50) Soviet models had spring-loaded firing pins, which held the pin away from cartridge primers until struck by the action's hammer, most variants of the SKS have a free-floating firing pin within the bolt. Because of this design, care must be taken during cleaning (especially after long storage packed in cosmoline) to ensure that the firing pin can freely move and does not stick in the forward position within the bolt. SKS firing pins that are stuck in the forward position have been known to cause accidental "slamfires" (the rifle firing on its own, without pulling the trigger and often without being fully locked). This behavior is less likely with the hard primer military-spec ammo for which the SKS was designed, but as with any rifle, users should properly maintain their firearms. For collectors, slamfires are more likely when the bolt still has remnants of cosmoline embedded in it that retard firing pin movement. As it is triangular in cross section with only one way to properly insert it (notches up), slamfires can also result if the firing pin is inserted in one of the other two orientations.
SKS rifles, with the exception of the Yugoslavian variant, the barrel is chrome-lined for increased wear and heat tolerance from sustained fire and to resist corrosion from chlorate-primed corrosive ammunition, as well as to facilitate easier bore cleaning.
The front sight has a hooded post. The rear sight is an open notch type which is adjustable for elevation from . There is also an all-purpose "battle" setting on the sight ladder (marked "П", for "Прямой выстрел", meaning "Straight shot"), set for . This is attained by moving the elevation slide to the rear of the ladder as far as it will go.
All military SKSs have a bayonet attached to the underside of the barrel, which is extended and retracted via a spring-loaded hinge. Both blade and spike bayonets were produced. Spike bayonets were used on the 1949 Tula Russian SKS-45, the Chinese Type 56 from mid 1964 onward, and the Albanian Model 561.
The SKS is easily field stripped and reassembled without specialized tools, and the trigger group and magazine can be removed with an unfired cartridge, or with the receiver cover. The rifle has a cleaning kit stored in a trapdoor in the buttstock, with a cleaning rod running under the barrel, in the same style as the AK-47. The cap for the cleaning kit also serves as a cleaning rod guide, to protect the crown from being damaged during cleaning. The body of the cleaning kit serves as the cleaning rod handle. In common with some other Soviet-era designs, it trades some accuracy for ruggedness, reliability, ease of maintenance, ease of use, and low manufacturing cost.
Development history
The Soviet Union utilized a number of semi-automatic as well as select-fire rifles during World War II, namely the AVS-36, SVT-38, and SVT-40. However, the primary service rifle of the Red Army remained the bolt-action Mosin–Nagant, which fired the powerful but heavy 7.62×54mmR round. Even prior to the war, the Red Army had recognized that these weapons were obsolete and initiated a program to modernize its existing small arms, although this was interrupted by the German invasion of the Soviet Union in 1941. Among the military development programs the Soviet Union had monitored in other countries were the Finnish, Swiss, and German developments in intermediate rifle cartridges. These had limited range and muzzle velocity compared to the 7.62×54mmR and other contemporary rifle rounds such as the 7.92×57mm Mauser and the .30-06 Springfield, but also possessed numerous advantages: they were cheaper to manufacture, permitted easier weapons handling due to their much-reduced recoil and muzzle blast, and enabled infantry to carry more due to their small size and light weight. They could also be fired from shorter and lighter rifles. The Red Army's interest in an intermediate cartridge was piqued when stocks of 7.92×33mm Kurz ammunition were captured from the Wehrmacht, and by the end of 1943, Soviet technicians had developed a similar cartridge based closely on the German design, the 7.62×39mm M43. Early trials showed that the new round had the penetrative capacity to pierce three panels of plywood, each of 2.25 cm thickness, at a six hundred meter range. Red Army officials believed this was more than enough power to wound or kill a soldier at typical battlefield range. Limited production of the new ammunition type commenced in 1944."Патрон – основа оружия. Глава третья. Из истории автоматного 7,62-мм патрона образца 1943 г. (7,62х39)", Оружие 2005/9, pp. 21–44
Hurried efforts were made to introduce a rifle capable of firing the new cartridge, and the first prominent design was offered by Sergei Gavrilovich Simonov. This was known as the Samozaryadny Karabin sistemy Simonova (SKS), or "Simonov's self-loading carbine system" Simonov had already been working on a semi-automatic carbine chambered for a lighter cartridge as early as 1941, owing to recent complaints about the effectiveness of the SVT-40. In fact, one of his earliest prototypes was chambered for the 7.62×25mm Tokarev pistol cartridge, which was also used in the PPSh-41 submachine gun. He also built at least one prototype chambered for the larger 7.62×54mmR cartridge. Unlike previous Soviet semi-automatic rifles, these utilized fixed five or ten-round magazines loaded from stripper clips. They were also distinguished by a large muzzle brake and a fixed gas system covered with a metal shroud. Simonov's design was based on the operating mechanism of the PTRS-41 anti-tank rifle he'd previously developed for the Red Army the same year. On 1 July 1941, the Artillery Committee of the Red Army noted in its records that the Simonov's self-loading carbine, designated SKS-41, satisfied its basic "tactical and technical requirements". The Committee praised the SKS-41 for its light weight and the design of its fixed magazine; it recommended that 50 pre-production models with ten-round magazines be presented to the Red Army for trials. The SKS-41 was to be chambered for the 7.62×54mmR cartridge for logistical reasons, as the Soviet government wished to adapt its existing rifle barrel production lines for the new carbine.
Red Army evaluation of the SKS-41 prototypes was shelved due to the German invasion, and did not resume until Simonov rechambered his weapon to accommodate the 7.62×39mm cartridge in 1944. He also made a number of other detail improvements to his original carbine, omitting the large and unwieldy muzzle brake, adding a folding bayonet, and replacing the metal gas system shroud with a removable wooden upper handguard and gas tube which housed the gas piston. The gas tube and upper handguard could now be removed as needed to access the gas port and piston for cleaning. The appearance of a 7.62×39mm prototype revived interest in Simonov's design, as only he and one other weapons designer, Alexey Sudayev, were able to produce rifles chambered for the new round on short notice. Sudayev's prototype was a less conventional, more compact assault rifle which more closely resembled the later AK-47. A second 7.62×39mm semi-automatic carbine contender was later offered by Mikhail Kalashnikov; this was based on the operating system of the M1 Garand. Kalashnikov's carbine appeared too late to participate in the Red Army's initial evaluation, and was rejected as the decision had already been made to submit the SKS for field trials.