Varieties of Yugoslavian SKS Grenade Launchers
The Yugoslavian SKS rifles, M59 and the M59/66 are very interesting variants of the SKS design. Differentiating the Yugoslavian SKS from other SKS variants is the difference in the gas operation of the rifle, as the Yugoslavian SKS introduced a cut-off to allow a "blank" to fire a rifle grenade. At the muzzle end of the barrel is the grenade launcher, and there are at least three major styles of grenade launchers encountered on Yugoslavian SKS rifles.
There is a fourth style of "grenade launcher" found on the Yugoslavian SKS rifles in the surplus market; a nicely finished smooth "grenade launcher" which was added in the U.S.A. to rifles sold in California. The reason is that the original style of grenade launcher is illegal in California. It is also possible to find these rifles in other states, for chain stores that sold the Yugoslavian SKS such as Big 5 operate in California and other states (Colorado, for example) and Big 5 only purchased rifles with the "CA-approved" replacement for the grenade launcher for sale in all their stores.
Type 1 Grenade Launcher
The first variety appears on early Yugoslavian SKS rifles, and the example below is from a H-series produced in 1971.
The two features to note with this type of grenade launcher is the porting and the square base of the retaining ring. This is the common grenade launcher style encountered on early rifles. The final ring of the grenade launcher has even spaced holes drilled.
Type 2 Grenade Launcher
The next variety lacks the porting of the grenade launcher. Early rifles without ported grenade launchers overlap production dates with non-ported grenade launchers, and a clear cutoff date is difficult to determine. This picture to illustrate the non-ported variety is also from a H-series rifle.
Since the dates of manufacture overlap, it is unknown if both styles were produced at the same time, or if the non-ported style was a later refurbishment to rifles with ports.
Type 3 Grenade Launcher
Towards the end of production, a running change was introduced that altered the style of the retaining ring base. The retaining ring base was tapered, instead of the square style encountered on earlier rifles. This example is from a U-series rifle produced in 1984.
The pictures below show, side by side, the square base and tapered base varieties: