OK Guys,

Here goes with what may be a STUPID but very important question. My apologies for the stupid part.

I need to vise up several Mauser actions (a Parker-Hale, a Mark X, 3 FN commercial actions, and a VZ.24) on a mill bed. I have the equivalent of a rail milling fixture, a mill vise, dial gauges, and a good DRO.

Where is the best place to indicate on a Mauser action to make sure one gets it straight on the mill bed and can find the center of the place the bore should be?

Thank you for your assistance!

quote:

Originally posted by mstarling:

Where is the best place to indicate on a Mauser action to make sure one gets it straight on the mill bed and can find the center of the place the bore should be?

Thank you for your assistance!

That would be the center of the bolt tunnel. The axis of the bore and the bolt tunnel should form one uninterrupted line from the muzzle back out throught the rear of the action making the center of the bolt tunnel the zero point for ALL machine operations. Everything should be square to that. In a perfect world.

Golly that part is obvious

So ... given that there is no place to put an indicator on "the center of the bolt channel" ... how do you do that?

(Told you this was a stupid question or at least the fella hearing the answer isn't very experienced.)

Oh... Okay. The easiest way would be to turn a mandrel that just barely slips through the bolt tunnel, kind of like a bore guide, only extending out the front and the rear of the action, then you indicate the center of each of the protruding ends.

I made a 1" shaft with the far end threaded to (as close to the action threads as I could make it.... 1.1-12) and the far end squared off in the lathe such that the thread always butted squarely against the inner ring of the Mauser actions.

The 1" section of the shaft is 5" long so I can chuck it in Vee-blocks or in the milling machine vise.

I can then turn the threaded end into the inner ring hard to be used to drill and tap scope mounts and to face the outer action shoulder even though it's hardly ever needed.

In this manner all the machining I do to the action is square and in line with the face, inner ring, and threads that the barrel attaches to!

If that helps have at it!

Should have been more specific ... these fellas are barreled actions ... and I am not the proud possessor of a barrel wrench setup.

How about indicating on the barrel and a bar machined to fit into the rear of the action?

Mike,
You remind me of a Japanese hooker that starved to death....apparantly no one took a "yen" to her....

You're a step ahead of her as unless the barrels are removed you're gonna be screwed!

quote:

Originally posted by vapodog:
unless the barrels are removed you're gonna be screwed!

Not necessarily. Turn that somewhat snug fitting mandrel and insert it in the receiver just like a precision fitted bore guide. Mount the barreled action on your mill table with the bottom flat of the receiver parallel to the table.

Install an indicator in the quill and run the table back and forth with the tip of the indicator riding on the side of the mandrel that is exposed through the ejection port, and that portion which is protruding out the back of the receiver. Adjust and square the action like you would the 'fixed jaw' of a milling vise. Now all you have to do is locate center on the mandrel and set your dials to zero. This should get you close. For a better alignment you really need to pull the barrel and run the mandrel out the front of the action. Preferably the distance to where the throat would sit.

Guys,

Thanks for the comments!

Good to know that for precision machine work I need to have the mandrel to locate dead center of the bolt channel. Had not thought of that before as I've never had to do it.

The actions were squared and barreled by Douglas. I want to locate them on the mill bed pretty close to square so I can finish milling scope bases being fabricated for the rifles.

Thought I'd get them close on holding fixtures, move the bases to the action, and finish them. Not actually cutting the actions (I hope!).

Only challenge will be the VZ.24 which was drilled off angle in the back. Have made that base oversized so it can be milled on the action to straighten things out. For that one, I'll have to locate the approximate center of the rear end to make sure the mounts come out straight to the bore line.

I think the installation is not as critical as if I were actually cutting the receiver and the scope adjustments should make up for some error in the cutting of the bases themselves.

Is this yet another case of foolish expectations (things are square inside and out) or does it make sense?

quote:

Originally posted by mstarling:

I think the installation is not as critical as if I were actually cutting the receiver and the scope adjustments should make up for some error in the cutting of the bases themselves.

Set your alarm, you are in for a rude awakening!

Hope you're not doing this to an original sporting Oberndorff Double Square Bridge.

Don't laugh.....it's happened before!

Dearly Beloved! NO, five of these actions are common place, decent post 1960 commercial Mauser actions. Decent but nothing historic and (frankly) nothing special. One is a pretty decent VZ.24 of 1937 vintage.

No significant loss if I bubba a base. They are about $1.50 worth of 12L14 steel. The commercial Leupold steel bases should go right back on.

The bolt bore on Mausers is close to parallel to the flat bottom of the receiver, within .001"/1".

I do the barrel work with respect to the bolt bore, but the sight work and charging hump milling with respect to the flat bottom.