When I meassured the gun barrel, I found out, comparing with the Boudriot drawing, that the position of the trunnion is correct.There is a problem with the balance because the position of the Trunnion (gun ear) of the barrel is about 2 mm too far forward.
I think I should change the position of the Trunnion, but I don't have the tools and skills, so I changed the position of the Gun carriages receiver.
The problem is, that the barrel is not drilled, only the first mm, so that the weight in front is too big - with this they are prone
I drill the barrel for appr. 1cm, but only to have the imagination of a "hole" - the unbalance of the barrel I solved with a drop of glue