Just another study sketch for a "Rosemary and guns" piece that I've wanted to do for awhile. The HK21 machine gun was Heckler and Koch attempt to establish themselves in General Purpose Machine Gun market. Unlike other areas of the military/ law enforcement market, HK has not been a major player here. Based on the very successful G3 rifle platform the HK21 did offer several advantages. For countries that were already using the G3 rifle it made familiarization with the weapon much easier for the troops. It could configured to fire from either belt or with some minor modification standard G3 magazines. It also feature a quick change barrel which many armies demand in a GPMG.

So why didn't it succeed when other HK products have been so successful? A couple theories have been proposed.

One, West Germany already had a GPMG that had survived the harshest product-testing know to man, WWII, in the MG3 which was a modernized version of the MG42.

Two, any army that wasn't already happily armed with the MG3 was either using old war surplus machine guns. or was using Warsaw Pact equipment or the US M60 from their patron state's supplies. Finally HK had to compete with FN's now famous MAG58, US. M240, which was designed specifically for the GPMG role.

Three, while the HK21 was a good GPMG by many accounts it was not a great GPMG like the MG3 or MAG58, or the Soviet PK/ PKM. It is an example of "good is the enemy of the best".