Hi.

The nominal dimention of the rod is 7/31", or 5.55mm. Finding rods above og bellow within 0.1mm tollerance is what I would find acceptable.
The Stomperud barrel front dia is done so the front band for the m94 rifle fit the barrel dia, and that the front sight from the m94 fit. The dia and contour of the carabine 1916 is differerent from the rifle, only the muzzle dia of nominal 15mm is the simmular.
There must be a record of what serial were made to Stomperuds in 46-51 at Kongsberg, but I do not have it, and do not know were to get hands on it.