7.62mm NATO was the standard NATO rifle cartridge adopted after the Second World War.
This round is sometimes referred to by its case length (i.e. 7.62 x 51), or by its civilian designation of .308 Winchester (.308 being the Imperial measurement, or calibre).
Several types of 7.62 mm ammunition were issued for use with the FN C1 and FN C1A1, the FN C2 Light Machine Gun and the C1 General Purpose Machine Gun - all of which were replaced by 5.56 mm weapons in 1985, with 5.56 mm becoming the new NATO standard. The 7.62 mm rounds continued to be used after 1985 by the C6 GPMG.
Pictured below are the major machine gun rounds issued in 7.62 mm - ball ammunition, tracers (red tipped) - generally issued out 1 tracer to every 4 rounds of ball ammunition, the standard for use against personnel, armour piercing (not available via the Canadian Forces supply system but obtainable through US sources in Europe), a "dummy" or "drill" round, used for gun drills, and blank cartridges for use in exercises. Additionally, Inspection Cartridges were also issued, identified by a chromium case and absence of a flash hole, used by armourers and weapons technicians. From the left - Ball, Tracer, Armour Piercing (US), Dummy (Fluted) and Blank cartridges.
The C33 blank cartridge was also issued out with the grenade launcher for the FN C1/C1A1 Assault Rifle. This round had a flat head and was used exclusively to project grenades from the launcher, which was attached to the muzzle of the rifle.
Tracer rounds are used to assist machine gunners in laying their weapons on target; chemicals in the base of the projectile start to burn and give off a glow at a distance of about 125 metres from the weapon, burning out at approximately 800 metres.