On one of the Russian forums (I'm from Ukraine, I know the language) I found a post of a guy who added a Z-6 model to WP_RAPID_FIRE_CONC. As I understand it, the above weapon are considered "unused". And there's no way to spawn him. Accordingly, when I write "give/spawn weapon_rapid_concussion" in the console, nothing happens.
Perhaps someone knows a fix / mod that will allow you to take WP_RAPID_FIRE_CONC into the hands of the player. If there is one, please share.
And here is a screenshot with a rotary blaster Z-6.