The Zastava M90 is the modified version of Zastava M80, itself a version of the Zastava M70 (chambered in the Western 5.56×45mm NATO round), also comes with a flash eliminator and different magazine design, which means that like its predecessor, the M90 is a modified Soviet AKM. It is gas-operated, air-cooled and magazine-fed, shoulder fired weapon with selective fire capability, and like M70, can launch rifle grenades and has a rifle grenade sight added on the gas tube, instead of under barrel grenade launcher like on most other AK variants. It also incorporates the adjustable gas system from its M76, M77 and B1 cousins, with the third gas position being the gas cutoff for grenades.
Like all Zastava-produced AK variants, the M90 can be identified from the originals by its longer lower wooden handguard design, which has three cooling vents, no bulge and like the stock, is made out of different wood type. Also, due to using Western round, this particular model also has different magazine design, similar to Western STANAG and a Western type of flash eliminator, similar to one used on American M16 assault rifle. Like on the other Zastava AK's, this three-vent feature gives the M90 lower overheating when compared to the originals, but the Western round in this case, slightly reduces reliability.[citation needed]
