It's a pity you spent a lot of time trying to work from 2D drawings. A 3D scanner such as Creaform sells would produce what you need in minutes.
If you don't have a rifle to work with consider one of those non-firing replicas made in Spain that are sold in Europe at various places. I saw them for sale at Mont St. Michel of all places, so no doubt you can find one closer to home. Or a deactivated example would be another alternative.
WWI? You'll need a Ross MkIII as well!
“There are invisible rulers who control the destinies of millions. It is not generally realized to what extent the words and actions of our most influential public men are dictated by shrewd persons operating behind the scenes.”