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MODEL 99 jap rifle

kidthatsirish
Ok, so I have a Jap Model 99. I was told that the rifle i have had been rechambered for 30.06 vs what it used to be (the 7.7 jap round).

I fired 10 rounds of 30.06 from the rifle years ago and noticed after a while that there seemed to be a small (and I mean small) bulge near the based of fired brass. I thought this could be a saftey issue so I stopped shooting it.

I then found out that even if a Model 99 had never been smithed, it could still chamber and fire a 30.06 round although accuracy would suffer. So I figured this is what I had done.

I was told the Rifle was still in good shape by a "gunsmith" and so I finaly found some factory loaded 7.7 jap rounds. I fired two of them and noticed the following.

1) they also had a very slight bulge in the bottom of the fired brass (and once again, I meand small as in would need a dial caliaper to measure the differnce).

2)when i extraceted the 7.7 rounds, I noticed that the brass had been reformed in the chamber, the neck and shoulder "moved up" if you will so that it matches the spent 30.06 in terms of where the shoulder, and neck are.....it litteraly looked like someone had taken a 30.06 case, and cut of about an 1/4 inch from the top of the neck.


Ok....so I stopped shooting this rifle for fear it may blow up on me or something.

I then after cleaning it noticed that the bolt of the rifle did not match the numbers on the reciever...so it seems the wrong bolt is in my rifle.


Any ideas on what is going on? The chamber and barrel still look clean to my eye (though mine isnt trained by any means)

My guess so far is that it actually was rechambered for 30.06, and the slight bulge in the base of the spent brass is from the slight head space issue from not having the original bol that goes in that gun?

Any other ideas are welcomed.
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Comments

7 comments

Date Votes
  • Fatstrat
    A mismatched bolt could cause headspace issues that could result in your 1st problem.
    But my 1st interest would be to determine the Series number of your rifle. Basically the Jap T-99 falls into 3 catagories. Early, Mid War Transissional. and late war "Last Ditch". What this means is that as the war progressively went bad for Japan, the quality of the arms they produced went increasing bad. Until by 1944, the "Last Ditch" rifles were being MFG'erd by cottage industry, by unskilled labor (often school children), on worn tooling. And are at best, questionable as to how safe they are to fire. And your problem could be a result of this.
    A google search for "Markingson Japanese rifles" will lead you to a website that will help you decipher the markings on your rifle to determine Arsenal and Series. If you need further help, If you can post some clear pics of all receiver markings, I will try to translate them for you.
    The bottom line is that your rifle might not be safe to fire w/any loads.
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  • MIKE WISKEY
    A .30/06 WILL NOT CHAMBER IN A UNALTERED JAP. 7.7MM, SO YES YOURS HAS BEEN RECHAMBERED. THE SLIGHT 'BULGE' IS MORE OR LESS NORMAL IN ANY WAR TIME PRODUCTION RIFLE. YOUR RIFLE MAY NOT SHOOT THE BEST WITH NORMAL .30/06 AMMO AS THE 7.7MM USED A SLIGHTLY LARGER DIA. BULLET (.311" VS THE .308" OF THE /06).
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  • martinicadet
    At this point you need to have a chamber cast made to determine what caliber it is. If it is a 30/06 it will never shoot well since the 7.7 is 311 bore vs 308 bore for the 30/06. Either way I would hang it on wall and not shoot it.
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  • the yooper
    It may not shoot well due to the bore diameter, but you WILL NOT blow it up. Check out this article. http://findarticles.com/p/articles/mi_m0BQY/is_5_50/ai_114283920/

    yooper
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  • Hawk Carse
    Your rifle has been reamed with a .30-06 reamer.
    I have read that this was done with captured Japanese rifles to arm our then-new friends in South Korea with cheap guns we could supply ammunition for. Also done on cheap surplus guns sold in the states, of course.

    There was a guy on another board who maintained that the 7.7 was designed so that a Japanese soldier could cram .30-06 into the chamber if captured ammunition was all that was available. Pure BS, the guy was in the business for years and should not have swallowed that story.

    The 7.7 Jap is slightly larger in head diameter than .30-06, so the brass tends to bulge more than with the original caliber, even without counting the effect of a military chamber meant to be shot hot and dirty.

    Excess chamber headspace does not cause a radial bulge like that. You can hope that whoever did the rechambering did it with that bolt to check headspace with.

    Gunsmith examination would be wise, but it might cost more than the gun is worth.
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  • jonk
    If it were mine.....

    I'd handload the 30-06 in neck turned brass with .311" projectiles.

    Both mine bulge at the base slightly. Common enough as the base is in fact slightly larger than standard 06 brass. I wouldn't really worry about it. Even if it does crack the worst you'll get is a case head seperation and a stuck shell in the chamber, which for a $12 tool you can remove.
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  • Fatstrat
    I repeat. If it's a Last Ditch, it may not be safe to fire.......... PERIOD.
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