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Yugoslavian RB-100 Hand & Rifle Combination Grenade

The RB-100 is an interesting grenade type.
It is a combination hand or cup-launched rifle grenade. The body is cast iron and has an aluminum fuze. The cup is made from a brittle plastic, much like what old 45 rpm records were made of. (For you readers that are old enough to remember those.)

The cup has an outside diameter of 64mm (2.5"). Interestingly, it fits the British No.1 Mk.I grenade cup discharger perfectly. Coincidence or design?

The grenade is removed from the cup, exposing a white plastic safety cap which is unscrewed.
It may then be used in a conventional manner, by striking the percussion fuze to start the delay, or used as a rifle grenade by replacing the cup and launched using a cup launcher.
When fired, the force of the discharge pushes the cup up against the grenade, activating the time fuze.

Cup Launcher

Yugo AKM & Launcher

Here is the Yugoslavian AKM variation of the Avtomat Kalashnikov-47 with the cup launcher designed for the RB100.
The integral grenade sight flips up and blocks the gas port to the cycling mechanism so that all gas is diverted into the barrel for launching. With the sight down it will cycle as a regular AK.

An interesting specialized grenade system. The grenade itself doesn't seem to be very versatile in that there is no convenient carry device, as is provided by a safety lever. It isn't clear to me what advantage this system has over a more traditional projector adapter and a spigot launcher, especially since they made a spigot device for other rifle grenades. (See the M60P1 Page)

Thank you very much Walt, for filling in the cup launcher "mystery"!