Xander:
Well, you are certianly allowed to model yours however you like, but fluff says they have Blunderbusses, not Shotguns! 
Unless you were to convince the counsel of Sorcerers that we should adopt a new weapon, I will stick to Blunderbusses.
But actually, your idea is very similar to Grim’s:
https://discourse.chaos-dwarfs.com/t/6025
Cheers!