Oh my God, I didn't see that bear unit before!!
Impressive!!
Naitsabes, I think the Urugan cannon could be initally an idea from Gav Thope to supply Kislev of somekind of artillery. And it's possible he thought on the famous Stalin's organ (orgue?) used in the WWII, a mobile artillery (and cheap) weapon. A kind of this:
And yes, very similar to the imperial rocket launcher. But when Gav wrote about the Kislevite army list this model didn't exist yet.
So, for me, using this dwarf organ gun is completely appropiate. For that, Illumini, I question you: can I use your idea for my own Urugan Cannon?
P.S. By the way, fantastic work on Vexnar the Reaper (what about Valnir?!?!?)