What can you tell me about a training cartridge for the RPG-7 that consists of a 7.62x39mm tracer cartridge and a 7.62x39mm blank cartridge connected by a metal collar that has a primer on the side? Are the cartridges modified in any way? Does the primer in the collar fire both cartridges or is there some sort of firing pin inside? has anyone seen one of these devices sectioned? Which countries made these?