Dear 3Sixbits

What he said was. He was intending to order the barrels finished from Lother Walther.
I can/did only comment on my dealings with them, they would I believe be unwilling to produce 2 only short chambered barrels threaded, for a private customer. I get my barrels from the states for this reason.

Of course the lathe is running backgeared for the low speed, however this reduction in gearing also increases the torque of the machine. That is when you can sense the cut pressure.
All my reamers are live pilot and they are held in a floating reamer holder, with high pressure through the barrel lubrication/cooling.
My comment about oval chambers is because in order to produce the required downward pressure for the reamer to cut whilst rotating it, there is a tendency for a person to lean on the reamer holder handle nearest them.
If taking 10 thou out of a short chambered barrel it is not a problem.In fact common practice.
With respect you were not suggesting that, you suggested that he got an unchambered blank.
That is a hell of a lot of material to remove without scoring or ovaling the chamber.

You are obviously a very experienced machinist, perhaps you can do the whole procedure in a vise. Not one in a hundered would attempt it. I assumed from the tone of the origional post that this gentleman is not widely experienced. Even too tight a vise can distort the chamber. Many benchrest gunsmits will only chamber in steady rests rather than through the headstock because of jaw pressure on the chamber area.

I have never cut a rifle chamber on a mill so I defer to your experience.

Thats a good way to do revolver cylinders. I don't have a milling machine. I cut the bolt stops/cuts on a dividing head on the lathe with a modified woodruf cutter and then line bore the cylinder by hand using hardened bushes in place of the barrel. As you said more than one way to skin a cat.

Regards