Unknown chamber in my Arisaka!!

[Char-Gar]

There were a number of blown out 30-06 wildcats "back in the day". That is not an Ackley shoulder. I believe it to be a 30-06 ICL Caribou. Look in Ackley's Hanbook For Shooters and Reloaders on page 427. ICL stood for Increased Capacity Loading. The ICL is quite similiar to the Ackley, but has a sharper shoulder angle.

[wallenba]

I don't have that book Char-Gar, but I'll look around. I did manage to get a chamber casting today. Click three times for biggest pic.
Not my best cast.
Just looked at ICL cartridges on Wikipedia. I think you've put me on the right path Char-Gar. They don't have dimensions though.

[Multigunner]

I hate to say it but it looks to me as if someone deepened the chamber with common drill bits rather than a chambering reamer, stopping when a .30-06 cartridge would chamber.

The angle of the shoulder looks like the angle of the point of a drill bit, and the forwards portion of the chamber cast looks cylindrical, or at least much less tapered than the rear portion.

Still if it shoots well enough to fire form cases without bursting them you still have a shooter.

If you want to recut the chamber to a commonly available cartridge perhaps one with a belted magnum case would clean up this chamber.
I seem to remember a British magnum with the same bullet size as the .303, but its long obsolete.

[Char-Gar]

If the chamber neck is big enough to hold a fire formed 30-06 round loaded with a 7.7 bullet, then you should have no trouble loading for the rifle. Just fire form a 30-06 case, neck size and go for it.

[wallenba]

If the chamber neck is big enough to hold a fire formed 30-06 round loaded with a 7.7 bullet, then you should have no trouble loading for the rifle. Just fire form a 30-06 case, neck size and go for it.

That's the plan as of now. Chamber neck is plenty big @ .344. Got to figure out how I'm going to neck size though. I will continue to try to determine the chambering, so I can have it stamped on the reciever someplace, as I may not always own it. I would never sell it without the buyer being fully aware. It no longer has any historical significance to me, so sporterizing it might happen too. Too bad, it has an intact mum and aircraft sights.

I shudder to think what might have happened if a novice bought it and fired a full load of off the shelf ammo.

[Multigunner]

That's the plan as of now. Chamber neck is plenty big @ .344. Got to figure out how I'm going to neck size though. I will continue to try to determine the chambering, so I can have it stamped on the reciever someplace, as I may not always own it. I would never sell it without the buyer being fully aware. It no longer has any historical significance to me, so sporterizing it might happen too. Too bad, it has an intact mum and aircraft sights.

I shudder to think what might have happened if a novice bought it and fired a full load of off the shelf ammo.

I've occasionally heard of useable take off barrels from these rifles being available.

With an intact mum it might be worth looking for another rifle thats already been altered but still has intact barrel and swapping barrels.

[Char-Gar]

I should think a 30-06 neck sizing die and expand with an M-Die of the correct size. In theory the Jap has a barrel groove of .311 over the 30-06 of .308. That is well within the reach of our M-Dies.

Take a micrometer to the fired case, near the head. The Jap case/chamber is larger in that area than the 30-06. Compare it to a standard 30-06 case at the same point. You don't want the chance of having a head seperation. Not much chance with fireformed cases and cast bullet loads, but could be an issue with full snort jacketed loads. The right way (according to Ackley) to chamber these rifles to 30-06 is to set the barrel back a few threads when the rechambering is done, to get rid of this potential problem.

[skeettx]

You can carefully neck size with 32 S&W dies, or 32 Auto Dies, or ??
Same with expander dies
To seat the bullet you can most likely use 30-06 dies backed away from the shell holder.
Mike

plus
http://www.gunbroker.com/Auction/Vie...Item=291080960

[wallenba]

[QUOTE=Char-Gar;1755433]I should think a 30-06 neck sizing die and expand with an M-Die of the correct size. In theory the Jap has a barrel groove of .311 over the 30-06 of .308. That is well within the reach of our M-Dies.

A 30-06 neck sizer could only do a partial sizing I think. The slope of the 30-06 shoulder would hit the new shoulder before coming all the way down. Unless the dies have a generous amount of clearance.

[leadman]

I have Hornady neck sizers in several calibers. I think they make a 31 caliber. Then use a 35 Whelen sizer for the body.
Redding make a body die but dont know if they have what you need.
I have had a 30 Gibbs in my hand and that looks very similar. The gibbs was usually expanded hydraulically to minimize the case lose.
Also if the '06 case proves to be too short the 280 Rem. case is longer.

[Hang Fire]

Could be a 30Gibbs.

http://www.30gibbs.net/Loads.htm

Ditto. I had a .35 Gibbs (.30-06 case fire formed) and it had the same sharp shoulder and very short neck.

[Char-Gar]

I don't think it is a 30 Gibbs and the Gibbs round has a much shorter neck that the standard 30-06 case. Rocky Gibbs shortened the neck and blew out the case to give greater powder capacity.

The fired round (pic #7) shows the neck of the new chamber to be the same length as the standard 30-06, which is what leads me to believe it is the ICL round.

[wallenba]

I loaded up three rounds of 30-06 with 21 grains of SR-4759 under a .313 sized Lyman 314299. Gonna get out friday unless it's too da&* hot! The range officer, Rick, knows I have an issue with this rifle. Hopefully he won't object. Should have a better idea of it soon.

[Char-Gar]

Sounds like a plan. Keep us posted on how things go.

[wallenba]

Well it's been a couple of weeks since my last post on this issue. I have not gotten out to fire those 30-06's yet, but I do believe Char-Gar has solved it. I just got my hands on P.O. Ackley's 1962 edition of "Handbook for shooters and reloaders". It's a copy provided by this company http://www.cornellpubs.com/old-guns/...p?item_id=3136 The repro is fair, and everything is there. The illustrations are to scale and my fired blown out 7.7 Jap and chamber cast match exactly the 30-06 ICL Caribou. After I get those 30-06 test rounds fired I should feel confident enough to order a neck die and possibly a seater if I need one. Thanks everyone, and a special thanks to sharp eyed Char-Gar.

[fatelk]

For dies, you might see if a set of Lee collet dies would work. I bought a rifle in 30-06 AI some years ago and was looking into buying special dies when I discovered that the standard 30-06 collet dies I already had worked fine for the Ackley Improved version.

[wallenba]

For dies, you might see if a set of Lee collet dies would work. I bought a rifle in 30-06 AI some years ago and was looking into buying special dies when I discovered that the standard 30-06 collet dies I already had worked fine for the Ackley Improved version.

The ICL's have a 45 degree shoulder which might interfer with neck sizing. I have some 30-06 dies and will try them first before ordering. The ICL's are in the 'obscure' rifle die section at Midway, and are $92 each with a 90 day wait too. So I'll try anything first.

[Char-Gar]

You are very welcome. Sometimes it helps to be old and sometimes not. Good shooting.

[Four Fingers of Death]

This old war horse is sure keeping you out of mischief!

[madsenshooter]

It looks to me like the 30-06 JDJ is another possibility. Here's the drawing of it: http://ammoguide.com/?catid=528 John Sundra also made some wildcats on the 30-06 case with the shoulder blown forward.