SIG SG 540
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The SG 540 is a 5.56×45mm NATO assault rifle developed in the early 1970s by Schweizerische Industrie Gesellschaft of Neuhausen, Switzerland as a private venture primarily destined for export markets and as a potential replacement for the 7.5×55mm... Wikipedia
Action: Gas-operated, rotating bolt
Barrel length: SG 540: 460 mm (18.1 in); SG 542: 465 mm (18.3 in); SG 543: 300 mm (11.8 in)
Cartridge: SG 540, SG 543: 5.56×45mm NATO; SG 542: 7.62×51mm NATO
Effective firing range: 100–500 m sight adjustments
Feed system: 20- or 30-round detachable box magazine
In service: 1977–present
Muzzle velocity: SG 540: 980 m/s (3,215 ft/s); SG 542: 820 m/s (2,690.3 ft/s); SG 543: 875 m/s (2,870.7 ft/s)