Unknown chamber in my Arisaka!!

[wallenba]

Just solved a long overdue problem with my M95. Today I got my type 99 out for the first time since I got it. It took a while to scrounge brass. This is what I got when I fired it.
Anybody want to guess what this 7.7 was rechambered to? Gander Mountain sold it to me as a 7.7 too. So much for their safety assesments of used firearms. The case was stuck in the chamber, but not too much effort to get it out. The primer is backed out about half way too.
Click three times to enlarge

[bruce drake]

most likely its a 30-06 reamer than has been used to recut the chamber. If you have a 30-06 case available, I would compare the two side by side.

And go back and yell at the idiot at Gander who sold you a potential accident/explosion.

Bruce

[wallenba]

Bruce, the new shoulder is about .160 higher than a 30-06. One guy at the range mentioned something about an Ackley improved something. Too much noise to hear it correctly. Rifling is untouched. It still has it's chrome lining and Metford rifling.

Note: a full length sized 30-06 does chamber. But new shoulder would be around the bottom of the neck. Did P.O. Ackley ever develope a 7.7-06 Ackley Improved?

[Dutchman]

Left to right:

.30-06
7.7x58 fired in '06 re-chambered Arisaka
7.7x58 handload Norma case (mine)

http://images46.fotki.com/v1416/photos/2/28344/3886627/ari1-vi.jpg

[wallenba]

Here they are with a 30-06 case. left to right, unfired 7.7, same fired, and 30-06.
It is safe to say this is not a 30-06 chamber.

I don't know why but sometimes my pics don't enlarge. This is a new computer with a different photo program. Got to figure this out, and get a better pic. See pic post #7

[Box13]

The shoulder reminds me of an Ackley improved...improved what I dont know though...Robin

[wallenba]

Try this pic. Click three times, to get back home Dorothy. (sorry, that just popped in my head)

Ackley is what I'm thinking too Robin, by the shape of it, but should I assume the parent cartridge is a 30-06?

[shredder]

Time for a chamber cast. A micrometer/calipers and a copy of "cartridges of the world" should solve it.

[wallenba]

Time for a chamber cast. A micrometer/calipers and a copy of "cartridges of the world" should solve it.

I'm looking for my Cerrosafe to do that. I remember buying it and not using it.

The mystery deepens. I found dimensions on 30-06 Ackley Improved. It shows 2.00 from the bottom of the rim to the shoulder. My fired case measures 2.090 which matches a 280 Ackley Improved. But since my primer was able to back out 0.019", what does that mean? Should I add that to that dimension? Why use a 280 chamber reamer on a 7.7? And since the short 7.7 Jap brass ran out of material and pressure, is it a true representation of the chamber? The shoulder does have a little irregularity to it.

My plan; Make a chamber casting. Determine length of neck. Trim 30-06 case/s to fit. Use a reduced load of TrailBoss under a .312 cast boolit. Shoot it, with shot bags stacked over reciever.
I don't really expect anything dramatic. That would have already happened with the 7.7 Norma cases I loaded.
This might work out in my favor, as 30-06 brass is everywhere. Took me weeks to get 40 7.7's.

[Multigunner]

The Arisaka is one tough action, only incidents of kabooms I've heard of was when some kids fired three rounds of .35 remington though a 7.7 with the receiver letting go on the third shot putting fragments in the shooter's brain, and one gunsmith reported having accidentally put a 7.92 cartridge in a 7.7 when firing remotely in a testing booth.
Chamber neck clearace is more important than bullet to bore fit, so I'd be very careful to find out the chamber neck ID before doing much shooting.



Why use a 280 chamber reamer on a 7.7
Theres been a reported instance of a 6.5 rifle rechambered to .30-06 by someone who did not realize the true bore size.
Could be someone thought the bore was 7mm rather than 7.7mm.

[RayO]

Could be a 30Gibbs.

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

[wallenba]

Could be a 30Gibbs.

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

Hmmmn....interesting. Is that a wildcat? Have not seen that one in my books. Gotta go look.

Found my Cerrosafe. Gotta get it apart and clean it good, and find something to pour it with. I can actually melt this stuff with a heat gun. Today I have to go out and play with the other kids though.;-)

[wallenba]

The Arisaka is one tough action, only incidents of kabooms I've heard of was when some kids fired three rounds of .35 remington though a 7.7 with the receiver letting go on the third shot putting fragments in the shooter's brain, and one gunsmith reported having accidentally put a 7.92 cartridge in a 7.7 when firing remotely in a testing booth.
Chamber neck clearace is more important than bullet to bore fit, so I'd be very careful to find out the chamber neck ID before doing much shooting.


Theres been a reported instance of a 6.5 rifle rechambered to .30-06 by someone who did not realize the true bore size.
Could be someone thought the bore was 7mm rather than 7.7mm.

Think the bore is OK. I slugged prior to loading. Near as I could figure it was a .313. The round fired was a .314, The Metford type rifling is a bit confusing when measuring. Definately not a 6.5 though. The fired case has a neck I.D. blown out to about .320, the O.D. is .344. Plenty of room there too. Question now is where chamber neck stops. Don't want a stuck case from overhang.

[flounderman]

it looks to me like it is just a normal 30-06 chamber, with a .312, or there abouts bore. You should be able to use regular 06 brass, neck sizing only. unless it was done by a non professional, it should be marked on the barrel. your primer is a sign of headspace. the primer backed out because it was not supported when it ignited. just neck size the cases, about half the length of the neck. initally, open a 30-06 case up by running an 8mm inside expander button thru the neck. then leave a little of the 8mm when you size it to 311. you want some resistance when you close the bolt. just keep trying to see how much 8mm you can leave and still close the bolt. I believe the 7.7 chamber is slightly larger at the base than the 06, so you should be able to chamber an unsized 06 case. after you have cases fired in the rifle, don't size the neck all the way to the shoulder and headspace will correct it'self

[flounderman]

the gibbs improved calibers were blown out to where the neck was extremely short and the shoulders were almost square. the ackley chambers moved the shoulder ahead and sharpened the shoulder angle, but not as radical as the gibbs. your shoulder angle is the same as a normal 06 it appears from the picture. it wasw a common practice to chamber the 7.7 to 30-06 and the 6.5 to 257 roberts. if you didn't handload, you could shoot factory ammunition. bullet fit was a little loose but you could probably get hunting accuracy. years ago, I bought a 7.7 for 3.50. barrel looked bad but was chrome and cleaned up. I cut the barrel to somewhere around 20 inches, and made a manlicher stock for it. I sized 06 cases in the chamber and trimmed them, loaded a case of 4831 and used pulled military 06 bullets. first group at 100 yards was 5 shots in an inch. it also shot the 115 gr 32-20 lead bullet good. I never measured the bore on that gun but it was at least 312 or more. japs run big. a lot of jap rifles were brought into the country as war souvenirs by returning service men and ammunition wasn't available so they chambered them to something that was available.

[skeettx]

OK, my two cents
Use a 30-06 case, barely seat a J* bullet, it should not let the bolt fully close.
Seat the bullet a little deeper, etc till the bolt will just close.
Then this will hold the case back against the bolt head for fire forming.
And I second the use of 4831 for a case full.
Mike

[Multigunner]

I remembered hearing of Thailand converting Arisakas to .30-06.
Looking about the net I found those rifles have a reputation for chambers being cut too deeply. New or nearly new rifles Thailand had earlier received from Japan were used for the conversions.

If one of these it should have Thai markings on the barrel over the chamber.
The converted rifles were called the type 83/88 and they called the .30-06 cartridge the Type 88 cartridge.

These had been 6,5 rifles so re boring or rebarrelings would have been necessary. I don't know if these had Metford rifling or if rechambered 7.7 barrels may have been used.

[runfiverun]

i got a "7.7" that had the bbl cut back slightly and chambered to 300 savage.
it was called junk and took me a few day's to figure out what happened to it.
it shoots quite well with 300 savage cases necked up for 312 jaxketed.
i also have a relined 6.5 to 257 roberts that has a weatherby double radius shoulder on it.
i had to relieve the extractor to slip over the rim better or it would bind on a case whether fired or not.
dang accurate and extremely ugly rifle right there [ it shot so well i had to go have it scoped after three groups] it had a set of williams sights on it that are now on my 44 rossi.
and a third thats in 6.5x257 it shoots about 18" high at 50 yds but does it pretty well..
and one that's actually in 7.7 that i made into a hunting rifle for my oldest girl.

once you cerrosafe the chamber i bet you'll find an 0-6 case will work for you just fine.
i had one once that had the chamber cut for the 0-6 correctly i even shot a couple of deer with it,it would have most likely been more accurate with larger bullets, but i was 16- 17 and didn't know any better, swapped it off for a 7 mauser [that probably had a 290 bbl on it]

[wallenba]

once you cerrosafe the chamber i bet you'll find an 0-6 case will work for you just fine.
i had one once that had the chamber cut for the 0-6 correctly i even shot a couple of deer with it,it would have most likely been more accurate with larger bullets, but i was 16- 17 and didn't know any better, swapped it off for a 7 mauser [that probably had a 290 bbl on it][/QUOTE]

My thinking too. A virgin 30-06 case chambers freely. Oddly though, a fired, full length sized 30-06 will not. I suspect the base has expanded too much. I don't have a base sizing die. The shoulder too, on that will exhibit some scoring from chambering. Possibly the die.
I did try a chamber cast late last night. I messed it up. Even with my bifocals I could not see well enough to control the pour. I got up into the locking lugs. I waited for it to cool enough to dig out some of it, and re-heat. Just made a mess. I just melted it out.

I have a RBH at my gunsmiths right now that will be picked up soon. I'll bring this Frankenstein with me then.

[wallenba]

[QUOTE=flounderman;1753354]it looks to me like it is just a normal 30-06 chamber, with a .312, or there abouts bore.

Nope, can't be a normal 30-06. The case on the far right in the pic shown on post #7 is a 30-06. Note that the fired case, a Norma 7.7, has a shoulder blown out much higher than the 30-06. I do believe that whatever it is, a 30-06 is the parent cartridge.

[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/ViewItem.aspx?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/item_desc.php?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.

[texassako]

A 30-06 Lee collet neck sizer should work well on that, and pretty cheap as well. It does not put downward pressure on the shoulder, less chance of collapsing it than a bushing die. It squeezes shut on the neck to resize it on the mandrel. You can also substitute a .311 mandrel since it is pretty easy to mix and match with these for other calibers.

[wallenba]

A 30-06 Lee collet neck sizer should work well on that, and pretty cheap as well. It does not put downward pressure on the shoulder, less chance of collapsing it than a bushing die. It squeezes shut on the neck to resize it on the mandrel. You can also substitute a .311 mandrel since it is pretty easy to mix and match with these for other calibers.

I concur. I took a look into my Lee 308 Win. collet neck sizer. It's completely open around the shoulder.
I talked to the pros at D & D Gunsmiths at Troy Mi. this week. If I can obtain a good 7.7 Jap. Barrel, I just might reverse this turkey. Options still being considered.

[wallenba]

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.

I looked into this possibility this morning. The link would not allow me to get anything without joining up. Feeling lazy I called SSK Industries. Actually talked to J.D. himself I do believe. He said if it was a 30-06 JDJ, he would have done the mod himself since he does not provide reamers. Also the fact it's not marked on the rifle means it's not his work. But it does look eerily similar.

[Pirate69]

The Arisaka is one tough action, only incidents of kabooms I've heard of was when some kids fired three rounds of .35 remington though a 7.7 with the receiver letting go on the third shot putting fragments in the shooter's brain, and one gunsmith reported having accidentally put a 7.92 cartridge in a 7.7 when firing remotely in a testing booth.
Chamber neck clearace is more important than bullet to bore fit, so I'd be very careful to find out the chamber neck ID before doing much shooting.


Theres been a reported instance of a 6.5 rifle rechambered to .30-06 by someone who did not realize the true bore size.
Could be someone thought the bore was 7mm rather than 7.7mm.

I think this is from the May, 1959 edition of the American Rifleman, page 52. At least that is what is reported on page 93 of BOLT ACTION RIFLES by Frank de Haas; MCMLXXI. The guy actually used it hunting and killed a deer. Took it to a gunsmith to have checked out because the recoil was excessive. Gunsmith fired a number of 30-06 rounds in it after knowing the situation. Wonder how that testing was done; brave man? Rifle later sent to NRA for additional testing. The Arisaka is one tough action even if it is as ugly as they come.

[Char-Gar]

Here is my input. The shoulder of the fired case is rounded and not very Ackley like. There was a family of Wildcats based on the 06 case called "ICL" Increased Capacity Loading that had such a shoulder. Therefore a 30 ICL is my best guess.

[wolfwing]

9 y.o. post, but I vote for 30 Gibbs

[slim1836]

I wonder if the OP is still around, he was on here last on 03-15-2019.

Slim

[Soundguy]

I've seen 7.7 cut to 30-06. That shoulder almost reminds me if a 300 Weathery mag

[oldblinddog]

When looking at the cerrosafe cast (not matched up with the brass) it doesn’t look like a .30-06 is the parent case to me. The ..30-06 is not long enough.

[Soundguy]

Shoulder really.really looks like a wm

[bigdog454]

If you are going to get another barrel, you could change to anything that uses a 06 or08 dim case. I had one rechambered to 6.5 X308 that was a really great shooter (under moa) the 6.5 308 is now the 260. just saying.
BD

[john.k]

All the Type 99s Ive seen have a chrome plated bore....apparently this is the "Marine model"......anyhoo,rechambering a chrome bore must be hard on reamers ......I counterbored a muzzle on one as there was a bit rust lifting of the chrome in the muzzle ,took it back about 1"......didnt do the drill bit much good.