The SIG SG 510 (Sturmgewehr 57 in Swiss service) is a battle rifle manufactured by SIGARMS (now SAN Swiss Arms) of Switzerland. It is based on the same roller-delayed blowback system used in the H&K G3 and CETME rifles. Hastily adopted in response to the Soviet invasion of Hungary in 1956, it was designed to fill the role of light machine gun, assault rifle, and grenade launcher. It is considered to be one of the most accurate mass-produced assault rifles available, and is very reliable in harsh climatic conditions at the cost of weight and being extremely over complicated (Sturmgewehr 57 historian Dale Ding notes the rear sight alone has more parts than a whole Makarov PM). The StG 57 rifle (chambered for 7.5mm Swiss) was issued to the Swiss Army. Later, the rifle was also offered for international sales, chambered in 7.62x51mm NATO as the SIG SG 510-4, but this variant has different external parts and was issued to the Armed Forces of Bolivia and Chile, who still use it to this day in a limited capacity.
