After the failure of the SIG 530 rifle (a gas operated, roller locked design), SIG looked for a much simpler rifle design, in both operation and manufacture. What they came up with was fundamentally AK-like, with a two-lug rotating bolt in a very AK-like carrier and a long stroke gas piston. The upper and lower assemblies of the rifle were both made of sheet steel stampings. The whole design is very easily disassembled, economical to produce, and reliable in the field. The main focus was on a 5.56mm version with hopes for Swiss military adoption (which would indeed come to pass). However, as a way to hedge its bets, SIG also scaled the rifle up slightly for a 7.62mm NATO sized cartridge, and designated this the SG 542.

Swiss law prevented SIG from selling rifles to foreign military powers, so instead SIG licensed the design to Manurhin of France. They made both military and civilian copies of the 540 and 542 between 1978 and 1988. The civilian copies were in .222 Remington and .243 Winchester, as French law heavily restricted civilian ownership of military caliber rifles at the time. Only a few were imported into the US, and this example from Larry Vickers’ collection also includes a very scarce original SG542-marked Hensoldt scope and mount.