An 'Artillery' Nambu and Lahti

[sheepherder]

Moving on to the barrel blank. It's from Green River, 308 cal, 4140 steel. Button rifled.

It's skim-cut for concentricity and inserted as far in the chuck/headstock as it will go...About 5 inches. I turn the end for the receiver stub, thread it, and make a nice snug fit. Then I relieve the last .030" where the stub threads into the receiver.

[sheepherder]

Chambering has been outlined in two previous threads -

Artillery Barrel Specs

http://forum.lugerforum.com/showthread.php?t=21048

and -

Alternative Artillery Barrel Fabrication

http://forum.lugerforum.com/showthread.php?t=25858

- So I won't repeat the steps here. Stripped bolt is used to set headspace and breech gap. Barrel is then removed and the middle is rough turned. The barrel is also milled flat on all four sides where the rear sight base will be, and then is set back in the lathe to turn off the front sight base section.

(The battery in my digi-cam crapped out while the milling operations were going on; my apologies).

[sheepherder]

Here's another thread on barrel fabrication & profiling -

6" .30 Luger barrel, 1900 style

http://forum.lugerforum.com/showthread.php?t=29518

Sometimes you get ahead of yourself...Which is what I did here...I left the muzzle nice & long to chuck it, but forgot that I needed to finish the muzzle [turn to dia, round, and crown] before milling the sight bases round...So I had to cut the excess off and finish the muzzle...

I used a 4-jaw chuck. Took about a half-hour to get the barrel centered.

I don't recommend this setup; I don't like the end being unsupported while it is being turned, but due to CRS it turned out this way. I took very small cuts and slow manual feed, and it turned out OK.

The centering in the 4-jaw is a PITA. It has taken me an hour in the past, to get it down to +- .001". This time I clamped a 7.6mm ground pin in my tailstock Jacob's chuck and hung the barrel on that, and ran the jaws of the lathe chuck up to the barrel for a rough centering. Then it was just all trial & error with the dial indicator to get it 'just right'...

[sheepherder]

Finishing up the muzzle. Clamping the barreled action in the mill and cutting the base, cutting the dovetail, and fitting the rear sight base. Worked out pretty well, I think. I'm using a Luger artillery rear sight. Doesn't look too bad.

[sheepherder]

First pic is just a mockup of artillery sight on blank; next is trimming back the excess metal where the sight mounts; third is cutting the barrel taper, a long tedious manual task, fourth is the tapered barrel, lightly polished, with sight mounted to see how it looks...

I am not a metal finisher, so there will be rough machined surfaces. These should blend in well with the rough Japanese machining...

Other pic is the polished taper...Compare with pic in previous post...

It's getting there...