Some information regarding the chemise from two French sources. I'll blame Bro. Larry and others for the translation
https://docs.google.com/document/edit?id=1CqqEj4qwaMwsSR7RkmHnUX5AvsVbUTUYr67VsZgzJ9QThe next operations take place at the factory and consist of breaking the core of the barrel by drilling the liner sheet with the aid of a square bit. The barrel is placed on a drill bench and held in a kind of vise while a square bit mounted at the end of a block operated by a hydraulic wheel turns in the core and removes the liner sheet which is fully welded to the barrel.
To make a good barrel, the chemise must be calculated on the thickness of the ribband, so as to this entève all with drilling. Maybe, for example, a gun having to be drilled with 17 mm in diameter; it will have to be finished of forging mill on a broche of 12 mm with a chemise of 12 mm thickness, which gives two for the diameter of them. The chemise enlarges rather; it does not decrease by tightening; it increases approximately 1 mm. Under these conditions, a drilling of 15 mm. to diameter the limits of the chemise while carrying it until would be enough to reach; to 17; there thus remain 2 mm. to take in the matter packed to free the curves and to give the interior polish, which is necessary and sufficient.
