He made a full scale mountain howitzer. From looking at only the materials presented on his website, the only barrel detail I really am not fond of is the plugged tubing. The interior joint between the plug and tube (the muzzle end, not the welded end) is going to be a place where corrosion occurs and it will be essentially inaccessible to address. Eventually it will become a safety hazard as a place for unextinguished embers to accumulate. If some way to effectively seal that joint is found, I would be satisfied.
My other complaint is with his carriage--a mountain howitzer stock does not have separate cheeks; they are part of the stock (at least on the pack carriage.) His carriage is more like a standard No. 1 carriage used by the Napoleon, Parrott rifle and wrought iron rifle.