Changing a NEF single shot to 30-06AI

[Mac11700]

Mac

[John Traveler]

Mac11700,

The Ackley Improved cartridges designed by PO Ackley all have one thing in common as stressed by their creator:  

To PROPERLY rechamber an existing chamber to the AI round requires that the barrel be set back one full turn (bolt, lever, pump, single-shot) before the re-chambering is done.  The reason, as stated by Ackley himself, is that to safely fireform factory cartridges in the new chamber, they must have 0.004" "crush fit" to properly support the cartridge shoulder.  Without this "crush fit", fired cases stretch from excess headspace and will not last.

Since your NEF .30-06  is a break-open single shot, I can see NO way to set the barrel back for proper rechambering.  Short-chambering the barrel would not work either because the existing chamber shoulder would give all of your fired cases excess headspace when loaded in your AI reloading dies, and put you right back to the excess headspace problem.

The other side of going to a wildcat is that rifles rechambered for non-standard cartridges will have significantly lessened resale value.

HTH
John

[John Traveler]

OOOPS!

I just re-read your posting, and see that your rifle is a .308 Winchester.

In that case, the rechambering to .30-06 AI is a straightforward reaming operation.

Sorry for the distraction!

John

[Mac11700]

Thanks

Mac

[John Traveler]

0.004" crush fit will make your NEF close hard.  The shoulder of the factory cartridge needs to crunch into the AI chamber shoulder to close the action.

You should have enough leverage to close on a cartridge with that much over minimum headspace.

A bolt rifle gives powerful camming action on closing, but your NEF barrel/forearm and a good grip on the stock will match that in closing the action.  It should be no harder than chambering a plastic shotgun shell that has been slightly crushed.

Let us know how you make out in the accuracy department.  Sorry that the mfr's have to give us all that grief with long chamber throats, but it's to their interest in the legal liability area.

HTH
John

[cronkite]

I had a H&R single shot in 25-06 and it was a pain to reload for. I had trouble chambering necksized cases. In fact if you didn't do everything perfect when you hand loaded the ammo the action did not want to close.If just neck sizeing causes problems, think about what the crushed fit of an Ackley will cause.
I would aproach this conversion with caution. Take and sell your 308 barrel on Ebay and have your receiver rebarreled to something else.

[Reed1911]

I'm not trying to be too much of a jerk about it, but is not the purpose of handloading to be prefect? If you want sub-perfection buy it off the shelf.

[cronkite]

I'm not trying to be too much of a jerk about it, but is not the purpose of handloading to be prefect? If you want sub-perfection buy it off the shelf.

Yeah, but what does this have to do with the crushed fit of the Ackley!!!!!!!!!

[Reed1911]

In fact if you didn't do everything perfect when you hand loaded the ammo the action did not want to close.quote]

The point of hand loading (more than the economy of it) is to build ammunition that is the best for your gun. If you are going to go through the expense of chambering to an AI, then reason stands that you will load for it appropriately. Using factory ammunition in an AI chamber is not meant to be a suggestion, just an option to be used if really needed. As a hand loader you'll be able to build your fire-forming load as needed and can adjust them for crush fit. I see no reason that if the chamber were cut properly that you would have any problem. The leverage from a 15" T/C barrel is enough to close and create a crush fit, I would think that a 22" (or so) barrel in the NEF will do fine. Beyond that the only time a crush fit will be necessary is in the forming process. It's a perfectly viable project, the receiver will easily handle the thrust from the .30-'06, and re-chambering to the .30-'06AI will actually reduce the thrust. I'm doubting that NEF/Marlin will do the re-chambering but your local 'smith most likely will.