Gre_tan tooling and fixtures

When I ground the outside of an action the arbor I used was turned to fit the action bore, it was tapered to fit the action bolt raceway bore because that bore was not straight. The action took .011 thou to clean up and now is concentric to the action bolt raceway bore.

The aluminum Gre-Tan fixture used to indicate the action in using the rods from Gre-Tan are they tapered or do you simply force the rods to contact one surface, say using extended scope base screws or the action bedding screws or do these bushings for the mandrel have tapered surfaces to center themselves in the action raceway? Buy the looks of the picture on their site the mandrel used to indicate the action in is really close to the bolt bore diameter, how thick or think are these bushings or is the madrel turned down smaller for the section that fits inside the action?

I understand how to use the fixture but am questioning the tapered bore. Maybe this was just my action but Remington’s manufacturing process leaves a lot to be desired in the realm of accurate machining.

If someone would be so kind as to go over how they use this it would be greatly appreciated.


Thanks

[kregg slack]

if you didn't live so far away i would say stop by and i would show you how it is done. the mandrel comes with bushings that are 0.702 0.7021/2 0.703 0.7031/2 0.704 0.7041/2 0.705 0.705 you use the bushing that fits tight in the back of the action and one in the front of the action then you take your mandrel and slide it into the bushings and processed to open up the race way to 0.705. then you put the 0.705 bushings in the action and slide the mandrel into the action from the front so it sticks out so you can dial the action in with your two gages. hers a picture of how you dial one in but i have a barrel in my jig i also dial my barrels in before chamber them.

[Fiftydriver]

Kregg,

Why is the mandral in your pic so small? The ones I have from Greg extend a full 6" out past the receiver face and are .705" in diameter.

Is that a different mandrel then Gregs accurizing mandrels?

Seems it would be much more difficult getting a receiver perfectly trued with that small distance between the dial indicators?

Just curious [img]/ubbthreads/images/graemlins/grin.gif[/img]

Kirby Allen(50)

[kregg slack]

that is a barrel that im about to crown, thats a bore rod i use to ture up my barrels before i chamber them and crown them. my tools for action blue printing are just like yours.

[tomindallas]

Kregg -

If I understand you right, when you ream it out to .705 using the bushings that fit the reamer and your action you're just opening up the raceway so you can bush the bolt. You're also providing a known inside dim for an arbor to index the rest of the machining off of (cutting the threads, facing the action and lugs).

So, what do you index in before this initial ream? The reamer with the spacers on it? If so, then Dave's question (as I read it) is still open - does the Gre-Tan tooling address any alignment problem between the outside surface of the action and the bolt raceway?

(I don't know how important that is in reality, this is just my favorite topic - truing actions)

Thanks for any insight.

[kregg slack]

the o.d of the action has nothing to do with anything. when you blue print one.

The only reason I did the outside was to make it concentric to the inside. The O.D. doesnt really matter as long as the bolt raceway and lug recess area are perpendicular to the I.D..
I wanted to see how much the action was out by grinding the O.D. I was told that the process used for the outside of the action is a rod that can be spun freely and the action is then beltsanded on this fixture by hand. This information comes from a buddy of mine who used to proof the actions for rem 700.
I understand more now that you've cleared up the bushing thing.