Improved Chambering

[Jetwrench]

I have read that you have to turn the barrel back to improve a chamber ( as in Ackley ). I would like to do this on a NEF Handy Rifle. Is it possible to be very careful and just ream out what is needed? Thanks for any help or insight. JETWRENCH

[Cap'n Morgan]

It depends!

If the cartridges headspace on the shoulder chances are high that you will have too much headspace after reaming, since the original cartridge must now headspace on a poorly defined radius between shoulder and neck.

If you're only shooting the standard cartridge to fireform brass for the wildcat you can compensate by seating the bullet to touch the lands, but I can see a legal problem coming up if you should ever sell the gun.

Your best option is probably to ream the chamber to a depth where a small part of the original shoulder remains, and then adjust the sizing die for the improved cartridge accordingly.

[badgeredd]

jetwrench,

I have built a few improved cartridge rifles with no problems. The first thing you need to do is check out the original cartridge compared to the "improved" cartridge. Rimmed cases are by far the easiest. In my 7x57 Ackley iImproved, I simply purchaced a go and a no-go headspace gages. Then I very carefully cut the improved chamber VERY slowly, checking the headspace with the go gage often. I didn't have any problems cutting the new cahamber. After cutting the chamber, I loaded up some shells with a relatively modest load (adequate to produce decent pressure which was the lowest load in the manual for the bullets I used) and fireformed the new cases. As said above, loading the shells so the bullet just touches the rifling is best because it keeps everything in place when the shell is fired. Headspace on most improved cartridges use a point on the shoulder that existed in the original cartridge. If you are concerned about that, one thing that will help is to expant the neck up a caliber or two, and then resize the case in improved dies.

Hope this helps you.

Just thinking about your question, and I want to say I have not headspaced a rimless cartridge in a tip-up action. I am thinking that one would want to get the action as free as possible so that one wouldn't get a false reading on the hadspace gage. Perhaps John Taylor will give you a couple pointers. He is a real gunsmith and not a hobbyist like myself. Just a thought.

Edd

[Jetwrench]

Thanks Guys, still rollin it over in my mind, but I will likley give it a try. Jetwrench

[Nobade]

You really don't want to do a rimless Ackley Imp on anything but a bolt gun. Nothing else has the camming power to close on a properly headspaced case to fireform it, despite what many will tell you. (to test if your setup is headspaced tight enough, just pop a primer in an empty case. If it sticks up, you have excess headspace.) Now a rimmed one is just fine, they don't need to be crushed to work.

[Willbird]

On the Ackley improved cartridges the chamber MUST be shorter than original to work properly, PO himself admonished people about this very thing.

Now IF you are using a case that can be made by necking down another case(say 25-06 made from 30-06 or 35 Whelen) you can probably get away with it by leaving the small shoulder left by necking down one caliber on the long side so the cases are a crush fit, once you have blown them out I would bump the shoulder .002 so that the rifle will close up/lock up consistently.

The end result however should NOT be stamped "22-250AI" for example because it is not chambered properly to be called that, a true AI chamber is .005" shorter than a normal "go" gauge for the cartridge, this allows firing factory ammo safely and results in proper fire forming with factory ammo.

[Jetwrench]

Nobade,
I was thinking on a 30-30AI and a 22/30-30AI so with the rim I should be ok.



"The end result however should NOT be stamped "22-250AI" for example because it is not chambered properly to be called that, a true AI chamber is .005" shorter than a normal "go" gauge for the cartridge, this allows firing factory ammo safely and results in proper fire forming with factory ammo."

Willbird,


is that true on rimed and rimless or just rimless. I don't have any Ackley experience, so please let me know.:confused:Jetwrench

[Willbird]

Nobade,
I was thinking on a 30-30AI and a 22/30-30AI so with the rim I should be ok.



"The end result however should NOT be stamped "22-250AI" for example because it is not chambered properly to be called that, a true AI chamber is .005" shorter than a normal "go" gauge for the cartridge, this allows firing factory ammo safely and results in proper fire forming with factory ammo."

Willbird,


is that true on rimed and rimless or just rimless. I don't have any Ackley experience, so please let me know.:confused:Jetwrench

On a rimmed cartridge there would be no difference, I have never chambered a rimmed ackley, not sure if you run the reamer in until it JUST kisses the old chambers rim recess ??

On the rimless proper chambering is a safety issue requiring barrel set back to do properly, on the rimmed that is not the case. It still might be worthwhile to set the barrel back so you get a nice new throat out of the deal, but not strictly required with a rimmed cartridge.

Bill

[badgeredd]

I just re-read my previous post and want to say I made a mistake (slip of the brain) that I need to correct. I did chamber the Improved chamber by reaming the old one out BUT I just remembered that I did indeed have a short chambered barrel to start with so in essence the barrel WAS set back as others here have said. I apologize to all for my error.

Sincerely, I mean it.

Edd

[GrizzLeeBear]

Nobade,
I was thinking on a 30-30AI and a 22/30-30AI so with the rim I should be ok.


Isn't the shoulder on the 30/-30AI moved forward anyway?