Gunsmithing Clocking a Barrel

[Mordamer]

If I tighten an action to a freshly cut shoulder by hand, how many degrees more rotation is 75 ft-lbs of torque going to turn the receiver?

I think that some of you have probably done this a thousand times and have a good estimate I can try.

 

[Gene Poole]

I typically see 7° to 9° when tightening the action. I use about 65 lb-ft with a lubricated thread. If you clock it, you'll see about 0.010 per degree of rotation on a 1.250 shank.

 

[LRI]

It's relevant to a few things:

Thread fit. Material hardness. Shoulder width. Type/quantity of lubricant used on threads. Surface finish of threads. thread pitch. Thread diameter.

There's no baseline answer I'm afraid.

 

[Mordamer]

It's relevant to a few things:

Thread fit. Material hardness. Shoulder width. Type/quantity of lubricant used on threads. Surface finish of threads. thread pitch. Thread diameter.

There's no baseline answer I'm afraid.

I didn't even think about thread pitch which should have been obvious. I will be installing a shouldered barrel onto an action with a savage tenon thread spec.

Action is a Shilen DGR. Barrel is a bartlein with 1.250" shank that is fluted. I will use an anti-seize compound as the lubricant.

I was hoping to be able to indicate the barrel on the lathe only once. I am going to time one of the flutes to top dead center. I don't want to have to remove the barrel from the lathe and the put it back on the lathe and re-indicate a second time.

 

[biffj]

You will probably need to fit the barrel at least once in order to determine where its going to stop. Looking at the thread will not give you precise enough info. So cut your thread and chamber then screw the receiver up to the barrel in the lathe to get an idea of where its stopping. No need to remove or re-indicate the barrel. In reality you should be able to flute with the receiver installed so you can put flutes where you want.
Frank

 

[majohnson2]

Just remember that with stainless it really easy to screw up the threads and not be able to get things apart.

 

[Danny1788]

I didn't even think about thread pitch which should have been obvious. I will be installing a shouldered barrel onto an action with a savage tenon thread spec.

Action is a Shilen DGR. Barrel is a bartlein with 1.250" shank that is fluted. I will use an anti-seize compound as the lubricant.

I was hoping to be able to indicate the barrel on the lathe only once. I am going to time one of the flutes to top dead center. I don't want to have to remove the barrel from the lathe and the put it back on the lathe and re-indicate a second time.

This is why I don't buy fluted barrels anymore. I buy them unfluted and have them fluted after I'm all done with clocking/timing the muzzle of the barrel to 12 Oclock, then I chamber and set headspace. I already have my TDC mark on the barrel from timing the muzzle and this is what I set the flutes off of.