How to set up an Ackley chamber w/barrel nut?

[benchracer]

It is my understanding that it is normal procedure to set a barrel back slightly when re-chambering to an Ackley cartridge in order to achieve the proper "crush fit".

If re-chambering a barrel that is retained and headspaced using a barrel nut, is the barrel still set back or would the headspace simply be set differently when the barrel is re-installed?

 

[shortgrass]

As it would be a new and different chamber, it should be set to the new headspace specs. The "GO" gauge for the parent case becomes the "NO-GO" for the Ackley version. Caliber specific headspace "GO" gauges are available for the Ackleys. Clear? Or, clear as mud?

 

[benchracer]

Actually, you hit on something I hadn't thought of. I had believed that the headspace gauges for Ackleys were the same as the standard counterpart. So, that helps.

But, does the barrel still need to be set back slightly for the Ackley to be done correctly on an action with a barrel nut retention system? Or would the Ackley re-chambering simply require the chamber to be reamed and nothing else?

 

[IdahoCTD]

Usually there is enough "slop" in a barrel nut system to run the barrel in another .003" provided the person cutting the chamber hits the depth just right.

 

[shortgrass]

A hobbiest can 'fudge' and fiddle only allowing himself .003"and hope all cleans up and headspace is correct. But, a set back of one full turn (.0625") is the sensable thing, for a working gunsmith. The head of the parent and the Ackley are the same diameter on paper, but the actual chamber and the Ackley reamer you're going to run into it may differ by a thou or two. When I do any re-chambering I want every surface of the chamber to be cut with the new reamer. No 'shadows' of the old chamber should remain. According to Ackley, himself, the Ackley chamber sould be .004" shorter than the parent chamber.

 

[IdahoCTD]

A hobbiest can 'fudge' and fiddle only allowing himself .003"and hope all cleans up and headspace is correct. But, a set back of one full turn (.0625") is the sensable thing, for a working gunsmith. The head of the parent and the Ackley are the same diameter on paper, but the actual chamber and the Ackley reamer you're going to run into it may differ by a thou or two. When I do any re-chambering I want every surface of the chamber to be cut with the new reamer. No 'shadows' of the old chamber should remain. According to Ackley, himself, the Ackley chamber sould be .004" shorter than the parent chamber.

The down side to that can be the neck diameter. If the Ackley reamer isn't at least as large or larger you'll have a stepped neck. Most new reamers seem to be on the smaller side of spec and a lot of factory chambers are on the larger side.

 

[Jim in Cali]

I just set mine up with an Ackley go-gauge to a slight crush fit. I've not fired it yet I want to do some Cream of wheat fireforming first with this one, usually I just fireform regular standard loads and be done with it.

 

[shortgrass]

The down side to that can be the neck diameter. If the Ackley reamer isn't at least as large or larger you'll have a stepped neck. Most new reamers seem to be on the smaller side of spec and a lot of factory chambers are on the larger side.

That's why you should make a chamber cast, first. Like about everything else I read on the web lately, folks would like to over simplify this, too. "Just stick a reamer in it and you're good to go". Stuff just don't work like that in the real world. Think, measure before you act. None of this is 'cut & dried'.