Developed by FN-Herstal (Belgium) as the Minimi light machine gun, the American version is called the SAW  for "Squad Automatic Weapon".  It is called the M249 in U.S. service.  Caliber is 5.56x45 NATO.  It is a belt-fed and magazine-fed light machine gun assigned to the rifle squad.  The gun itself has different variations of plastic furniture installed on it -- various configurations of forearm, fixed butt stocks, folding butt stocks, telescoping butt stocks -- and barrel various barrel lengths.  The gun carries a 200-round plastic box magazine for linked 5.56 NATO ammo beneath its balance point.  If the SAW gunner should run out of linked ammunition, he can use the 30-round magazines of either the M16 or M4 rifles to feed it from an angled magazine well on the left side of the weapon.  Heavier 7.62x51 NATO machine guns are found in the weapons platoon level of the company in supporting roles.  Navy SEALs are issued a product improved variation of the M249 called the Mk 46 Mod 0.  Certain reliability features have been added as well as Mil-Standard 1913 rails for the attachment of various sighting devices and other equipment.