Development of the domestic Kalashnikov variant began in 1959, and the first models submitted by Zastava for military field trials were with the early M64 (or M59) series of rifles with milled receivers, threaded barrels, familiar Zastava handguards, gas cutoffs for grenade launching, and several other diversities from the mainstay AK design, such as a bolt hold open device on the right side of the receiver, and a charging handle that appeared different from other AK models. Though performances were satisfactory, the Yugoslav military did not adopt the rifle as the standard infantry armament.
In 1970, was given the green light to begin with army-funded mass production of the AP M70 and M70 A series (Automatska Puška Model 1970, "Automatic Rifle Model 1970") of which the M70 A was the folding stock version.
Before the larger models of these rifles were made, cost-cutting measures in production resulted in the removal of the internal bolt hold open, and relocation to the magazine follower. In addition, the usual placement of the barrel through threading into the receiver was replaced by the cheaper method of pressing and pinning the barrel into the receiver. Rifles produced with these new features were known as models AP M70 B (fixed stock version), and M70 AB (folding stock version). As with the M70 series of automatic rifles, these models failed to be produced in larger quantities before further cost-efficiency production measures gave way to yet another model.
This time the milled receiver was replaced by a receiver stamped from a smooth 0.9 mm (0.04 in) thick sheet of steel, a firing rate reducer was added to the trigger group, and the muzzle brake replaced the muzzle nut that originally came on the two prior models; the produced models were AP M70 B1 (fixed stock) and M70 AB1 (folding stock).
These models eventually failed to mass-produce as well, before final alterations to the M70 rifle design resulted with the AP M70 B2 (fixed stock) and M70 AB2 (folding stock) models. These last two models featured a thicker 1.5 mm (0.06 in) stamped receiver and bulged front trunnion, which was intended to strengthen the rifle in order to make it more suitable for frequent grenade launching. These two models would become the most widely produced of the M70 series, and in turn the most widely used model used by the JNA, as well as the various armed groups fighting in the Yugoslav wars of the 1990s. Parts kits imported into the U.S. however, show markings that appear to contradict the final fixed stock model name. On these kits the bulged, thicker stamped receiver model is actually the M70 B1 model.
All of the M70 models share the grenade launching ability with gas cutoff, the lengthened wooden handguard with 3 cooling slots, iron sights with flip-up illuminating elements, initially filled with phosphorus and later with tritium (Which is used on the current production M70's), to improve aiming at night; the plunger that keeps the receiver cover in place during grenade launching, and a non-chrome lined barrel. Fire selectors have R markings for automatic fire (R for rafalna, "burst fire") and J for semi-automatic fire (J for jedinacna, "single").