The M78 was Valmet’s RPK-style heavy barreled squad support weapon pattern of the Finnish AK. It was initially developed as the M74 cavalry machine gun for Finnish military service, but never adopted. Instead, that experimental design would serve as the basis for the commercial export M78 (using the open notch sights of the M71, another design not adopted for military service). Had it been adopted by the Finnish military, it would have been chambered for 7.62x39mm (like the KvKK-62 squad automatic weapon that was used). For export, the company offered that caliber as well as 5.56x45mm and 7.62x51mm. Because these were imported before 1986, it was legal to manufacture them into transferrable machine guns, and this example is one that was so registered.