This project is officially finished. All the machine work is complete. I am quite satisfied with the final product.
I have determined that it would be relatively simple to convert a Luger artillery barrel to fit on a modified Nambu barrel extension ['receiver']. All it would require is to turn the Luger barrel threads down and re-thread; and cut, drill, and tap the Nambu barrel extension to accept it. The chamber might need to be deepened, and the Nambu extractor cut and feed ramp machined.
My 'artillery' barrel is not a direct copy of the artillery Luger. I like the Luger 1900 barrel band/base, and the Lahti 'square' front sight blade. My Luger artillery rear sight had been modified by a previous owner to a square notch, so I made my front sight blade squared also. A "Patridge" sight combination.
Similarly, it was easier to make the rear sight base simple rather than the complex concave & convex base of the Luger.
If it wasn't that I wanted the barrel in 30 caliber Parabellum, I would have modified a Luger barrel. I have only seen one 30 cal artillery Luger barrel for sale on GB in the last ten years, and it went for big bucks.
It would also be relatively simple to install a 'stock' Luger barrel of either caliber on a Nambu, using the method I outlined here. A 4 3/4" [120mm] Luger barrel in 30 caliber is almost a dead ringer for the OEM 8mm Nambu barrel profile.
I have to admit, this 'artillery Nambu' is even uglier than the original Nambu.
