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The HK21 is a West German 7.62×51mm NATO general purpose machine gun developed by Heckler & Koch in 1961.

Design details[]

The HK21 is an air-cooled, delayed blowback recoil-operated, select-fired, family of general purpose machine gun based on the previously made G3.

The gun can be configured to be belt-fed or use G3 magazines via an adapter, models chambered in 5.56×45mm NATO and 7.62×39mm, uses M16 and AK-style G3 magazines respectly.[1]


There are several variants such as:

  • HK11: A variant of the HK G3 with a heavier barrel, that could use 20 or 50 round magazines.[1]
  • HK11E: 3 round burst variant of the HK11, that used a trigger mechanibelt-fed or could be belt or mag fed.[1]
  • HK12: An LMG variant of the HK32, chambered in 7.62 x 39 mm.[2]
  • HK13: 5.56 mm NATO version of the HK11.[2]
  • HK13E: Version of the HK11E that is compatible with the M16 magazines.[2]
  • HK21A1: Belt-fed version of the HK21.[2]
  • HK21E: Improved version of the HK21A1 with a synthetic trigger.[2]