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Thread: Unknown chamber in my Arisaka!!

  1. #1
    Boolit Master
    wallenba's Avatar
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    Unknown chamber in my Arisaka!!

    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
    Attached Thumbnails Attached Thumbnails ArisakaChamber.jpg  
    Last edited by wallenba; 06-23-2012 at 12:28 AM.
    Dutch

    "The future ain't what it used to be".
    -Yogi Berra.

  2. #2
    Boolit Master




    bruce drake's Avatar
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    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
    I Cast my Boolits, Therefore I am Happy.
    Bona Fide member of the Jeff Brown Hunt Club

  3. #3
    Boolit Master
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    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?
    Last edited by wallenba; 06-22-2012 at 08:09 PM.
    Dutch

    "The future ain't what it used to be".
    -Yogi Berra.

  4. #4
    Boolit Master

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    Left to right:

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


  5. #5
    Boolit Master
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    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
    Attached Thumbnails Attached Thumbnails arisaka6.jpg  
    Last edited by wallenba; 06-23-2012 at 12:48 AM.
    Dutch

    "The future ain't what it used to be".
    -Yogi Berra.

  6. #6
    Boolit Buddy Box13's Avatar
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    The shoulder reminds me of an Ackley improved...improved what I dont know though...Robin

  7. #7
    Boolit Master
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    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?
    Attached Thumbnails Attached Thumbnails arisaka8.jpg  
    Last edited by wallenba; 06-23-2012 at 12:49 AM.
    Dutch

    "The future ain't what it used to be".
    -Yogi Berra.

  8. #8
    Boolit Master shredder's Avatar
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    Time for a chamber cast. A micrometer/calipers and a copy of "cartridges of the world" should solve it.

  9. #9
    Boolit Master
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    Quote Originally Posted by shredder View Post
    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.
    Dutch

    "The future ain't what it used to be".
    -Yogi Berra.

  10. #10
    Boolit Master
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    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.

  11. #11
    Boolit Bub
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    Could be a 30Gibbs.

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

  12. #12
    Boolit Master
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    Quote Originally Posted by RayO View Post
    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.
    Dutch

    "The future ain't what it used to be".
    -Yogi Berra.

  13. #13
    Boolit Master
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    Quote Originally Posted by Multigunner View Post
    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.
    Dutch

    "The future ain't what it used to be".
    -Yogi Berra.

  14. #14
    Boolit Master
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    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

  15. #15
    Boolit Master
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    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.

  16. #16
    Boolit Master



    skeettx's Avatar
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    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

  17. #17
    Boolit Master
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    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.
    Last edited by Multigunner; 06-23-2012 at 11:44 PM.

  18. #18
    Banned

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    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]

  19. #19
    Boolit Master
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    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.
    Dutch

    "The future ain't what it used to be".
    -Yogi Berra.

  20. #20
    Boolit Master
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    [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.
    Dutch

    "The future ain't what it used to be".
    -Yogi Berra.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check