The HK21 is a German 7.62 mm general-purpose machine gun, developed in 1961 by small arms manufacturer Heckler & Koch and based on the G3 battle rifle. The weapon is in use with the armed forces of several Asian, African and Latin American countries. It was also license-manufactured by Fábrica de Braço de Prata in Portugal as the m/968 and in Mexico by SEDENA as the MG21. In the German military (Bundeswehr) and the federal police (Bundespolizei) it is designated "G8".
HK21 with ammunition belts and bipod positioned at the rear near its point of balance
HK21 and bipod positioned at the front for maximum stability
Mexican navy gunners prepare to fire an HK21
Portuguese soldier with an HK21
The 7.62×51mm NATO is a rimless, straight walled, bottlenecked rifle cartridge. It is a standard for small arms among NATO countries.
Unfired 7.62×51mm NATO round (B) next to three recovered bullets, showing rifling marks (A)
.50 BMG, .300 Winchester Magnum, 7.62 NATO, 7.62×39mm, 5.56 NATO, and .22 LR
Service rifle cartridges loaded with projectiles: (left to right) 7.62×54mmR, 7.62×51mm NATO, 7.62×39mm, 5.56×45mm NATO, 5.45×39mm
7.62×51mm NATO cartridge case ejection from a British L129A1 Sharpshooter Rifle after firing L59A1 "High Performance" ammunition featuring a 10 g (155 gr) bullet
