Which riffle on which SIG SG 550 is based is a 5.56×45mm NATO assault rifle developed in the early 1970s by Schweizerische Industrie Gesellschaft?
SIG SG 550 The SG 550 is an assault rifle manufactured by Swiss Arms AG (formerly a division of Schweizerische Industrie Gesellschaft now known as Sig Holding AG) of Neuhausen, Switzerland. "SG" is an abbreviation for "Sturmgewehr", or "assault rifle". The rifle is based on the earlier 5.56mm SG 540 and is also known as the Fass 90 ("Fusil d'assaut" 90/"Fucile d'assalto" 90) in French/Italian or Stgw 90 in German ("Sturmgewehr" 90). 
FN FAL The FN FAL (French: "Fusil Automatique Léger" , English: Light Automatic Rifle), is a battle rifle designed by Dieudonné Saive and Ernest Vervier and manufactured by Fabrique Nationale d'Herstal (FN Herstal). During the Cold War it was adopted by many North Atlantic Treaty Organization (NATO) countries, with the notable exception of the United States. It is one of the most widely used rifles in history, having been used by more than 90 countries.