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Peter
06-04-2008, 08:33 PM
Would the best way to get a prefluted barrel timed be to run the threads way up under the recoil lug and cut from the shoulder what is needed to get the flutes where you want them?...Then chamber? TIA for advice :)

jackie schmidt
06-04-2008, 08:44 PM
If you are not a stickler for "same set-up" machining, you could finish everything, even cut the chamber real close, then screw the barrel on, torque it, and see where the flutes end up. Then, unscrew it, chuck it back up, and skin from the shoulder what ever you think it might need to clock the flutes where you wish them to be.
Then, chuck the barrel up again, and finish reaming it, using your measurements from the face of the action+recoil lug to the bolt face to determine your headspace.
Just be careful that you don't stack a bunch of tolerances in the proccess........jackie

BobB
06-04-2008, 09:47 PM
What Jackie said.

A good formula to help you determine how much to take off for alignment is to use the thread pitch and divide 1 by the number of threads.

For instance, 16 TPI would be a total of .0625 for each revolution of the barrel. You could get a pretty good estimate of how much to take off by setting it where it needed to be, marking it and figuring out how much movement you needed. A half turn would be 032, a quarter turn would be .015 and so on...all of this off of the face of course.

Dennis Sorensen
06-05-2008, 12:51 AM
Would the best way to get a prefluted barrel timed be to run the threads way up under the recoil lug and cut from the shoulder what is needed to get the flutes where you want them?...Then chamber? TIA for advice :)

That's what you have to do... the controlling thing is the flutes are indexed where you want them... then you have to do the final fitting and finish chambering... without screwing that up... or it is set back a few more thou...

Bnhpr
06-05-2008, 03:09 AM
If you are not a stickler for "same set-up" machining, you could finish everything, even cut the chamber real close, then screw the barrel on, torque it, and see where the flutes end up. Then, unscrew it, chuck it back up, and skin from the shoulder what ever you think it might need to clock the flutes where you wish them to be.
Then, chuck the barrel up again, and finish reaming it, using your measurements from the face of the action+recoil lug to the bolt face to determine your headspace.
Just be careful that you don't stack a bunch of tolerances in the proccess........jackie

Jackie,

Is it necessary to remove the barrel from the lathe, or could you bump it up enough without, and just check it?

I had a similar issue, trying to time up the barrel markings on a used barrel.

Ben

Jkob
06-05-2008, 08:53 AM
I don't think you could get it tight enough that way, it would probably slip in the chuck and spoil your setup.

The above answers are indeed correct. I normally machine the tenon to the demensions I need and then put the barrel in the barrel vise using a level across the top of the top flute, screw on the barrel, snug it up and using a bubble protractor, determine the degree needed to get that action level.

Like stated above, if you need, say 15 degrees, with a thread pitch of 16 TPI, one divided by 16, divided by 360, times 15 will give you the amount in thousndths needed to remove from the shoulder to get the two parts aligned where you need them.

Jim

Riflemeister
06-05-2008, 09:02 AM
The above advice is right on, but I set mine up so that running the action on by hand in the lathe, I come up 10 degrees short of where I want the flutes. This is on 16 tpi barrels, and when tightened in my barrel vise, you can get them right on without over or under tightening.