The SVD (), GRAU index 6V1, is a semi-automatic marksman rifle chambered in the fully-powered 7.62×54mmR cartridge, developed in the Soviet Union. The SVD was designed to serve a squad support role to provide precise long-range engagement capabilities to ordinary troops following the Warsaw Pact adoption of the 7.62×39mm intermediate cartridge and assault rifles as standard infantry weapon systems. At the time, NATO used battle rifles chambered in 7.62×51mm NATO as standard infantry weapon systems and had not yet adopted an intermediate cartridge and assault rifle of their own, allowing them to outrange their Warsaw Pact counterparts. It was developed through 1958–1963 and selected as the winner of a contest that included three competing groups of designers, led by Sergei Simonov (prototype rejected in April 1960), Aleksandr Konstantinov, and Yevgeny Dragunov. Extensive field testing of the rifles conducted in a wide range of environmental conditions (Konstantinov's competing 2B-W-10 prototype was simpler and cheaper but tested less accurate, durable and reliable) resulted in Dragunov's proposal being accepted into service in July 1963. An initial pre-production batch consisting of 200 rifles was assembled for evaluation purposes, and from 1964 serial production was carried out by Izhmash, later called Kalashnikov Concern. Since then, the SVD has become the standard squad support weapon of several countries, including those of the former Warsaw Pact. China produced a copy of the SVD through reverse-engineered samples captured during the Sino-Vietnamese War as the Type 79 and 85. Iran also produced a clone, the Nakhjir 3, which was a direct copy of the Chinese Type 79. Design The SVD bears a number of cosmetic similarities to the AK family of rifles but these similarities are for the purpose of standardizing manual of arms. This has occasionally lead to misidentification of the SVD as an AK variant, and vice versa. Operating Mechanism The barrel breech is locked through a rotating bolt (left rotation) and uses three locking lugs to engage corresponding locking recesses in the barrel extension. The rifle has a hammer-type striking mechanism and a manual lever safety selector. In addition to the trigger disconnect, the fire control mechanism has a second disconnector which does not allow the hammer to fall until the bolt has been closed, similar to a sear in a select-fire weapon. However, the SVD was only designed for semi-automatic fire. The firing pin in the SVD is not retained, i.e. "free-floating", and it is