Oddly enough the below ‘rocket’ is actually a rifle chambered in the 7.62x39mm cartridge! It is used in a RPG launcher for training purposes. I assume that it would be used in an actual RPG launcher and not a training replica.

I came across this link a PFOA post. From the website that sells it:

Used by the Czech military as a training aid to simulate firing a rocket propelled grenade using 7.62×39 ammunition. Features blued-steel construction with a rifled barrel, bolt assembly, knurled grips and yellow rocket head. The push-button type trigger assembly is designed to be fired while inside the RPG launcher itself (launcher not included or available), but it can be fired manually by depressing a small lever and pressing a recessed button in the rocket body.

Here is a video of it being fired: