The M60 is a general-purpose machine gun manufactured by General Dynamics (formerly Saco Defense) that is chambered for the 7.62×51mm NATO round. Referred to as "The Pig" during the Vietnam War due to its massive size and weight which totals to about 24 pounds.
Along with the M60 in Rainbow Six: Rogue Spear, there is are other variants of the M60 in the Rainbow Six universe. These variants are the M60E4 and the M60E3.
The 7.62mm M60 LMG machine gun was designed in the late 1940's and its initial design strongly borrows from from WW2 German developments. The 7.62mm M60 LMG was adopted by the US military in 1950. It has a belt of 100 rounds firing 7.62x51mm rounds with a rate of fire of 550 rounds per minute.
The M60E4/Mk43 Mod 1 features a redesigned machined aluminum feed cover with integrated M1913 Picatinny rail and an aluminum M1913 rail handguard provides for the mounting of optics, infrared laser aiming devices and other sensors giving the weapon 24 hour capability. The M60E4/Mk43 Mod 1 is a gas operated, disintegrating link, belt fed, air-cooled machine gun. It fires from an open bolt and features a quick-change barrel. In limited use by the US Navy (mostly Special Operations forces).