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7.7 Jap Rifle

Discussion in 'Gunsmithing and Repairs' started by boo586, May 6, 2003.

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  1. boo586

    boo586 Member

    Jan 3, 2003
    Well, I finally brought the 7.7 jap rifle back to Indiana from my dad's house this weekend. The gun is in pretty good shape cosmetically on the outside, but the bore is MINT!!!! I ran a boresnake through it today at lunch and it is bright and shiny with crisp rifling!!

    I can not find headspace gauges for the 7.7 jap so I am thinking about buying a box of the Norma ammo and clamping the gun to a shooting bench and firing a couple of rounds with a string attached to the trigger and then measuring the fired cases and comparing with pre-fired measurements.

    How do I go about giving this gun a thorough pre-firing cleaning?

    The numbers on the bolt match the receiver, but there seems to be some slop in the action when I work the bolt. Also, when I close the bolt it slides forward easily and then I have to put a good bit of pressure to close the bolt the last one half of an inch. It feels like a spring is compressing in the last half inch. Is this normal?

    Also, when I dry fire the gun (I know that I shouldn't be doing that, but it has been dry fired hundreds of times by my dad when he was a boy 40 some years ago) the bolt seems to rotate open just a hair. It doesn't rotate ope by any means, but moves visibly when dry fired. Is this a worry?

    Any help that fellow 7.7 Jap and other military rifle owners have would be very welcome and much appreciated.

    Thanks in Advance,

  2. eddieleon

    eddieleon Member

    Jan 1, 2003
    Buda, Texas
    Your description of the action is standard for all the Jap 7.7 I ever owned. They all cock on the closing of the bolt unlike the 98 Mausers that cock on opening of the bolt. Therefore the difficulty on the final closing of the bolt. You are compressing the spring for the firing pin.
    Also, the bolts seem to open slightly upon dry firing.
    Also, the good bore probably indicates a chrome bore. Look at the end of the barrel and there will probably be a silver ring at the bore about the thickness of a dime. If so you lucked into a chrome bored rifle. Don't think you can hurt it. Some I have seen hadn't been cleaned since brought home from the islands in WWII and still shined with an oiled patch.
    Also, The serial number and the bolt with the last three or four digits of the serial number indicates they were matched at the factory or at ordinace and should be head spaced correctly.
    Also, If the blue finish is good or indicates that it was a good deep blue originally, it was an early rifle and well made. Look under the forearm and you can tell what it was like originally in most cases.
    Remove the barreled action from the stock and remove whatever debris that has collected in the rifles 60 or 70 years of existance. Use a cleaner, diesel oil is a good cleaner for this and then degrease it. You can hold the trigger block down, punch out the pin in the action and then clean and lube the trigger and sear.
    Make ablolutely sure that the chamber is clean. I normally use a GI chamber brush for our 06 and it does a good side. Keep the chamber and barrel dry for firing.
    If you hold the bolt in one hand, push in on the safety and turn counter clockwise (I think) the unit will come apart in your hand.Use a rod and clean the inside of the bolt body, clean and lubricate the spring and firing pin and reassemble in reverse order.
    The last and final check is the stock. Those spare metal pieces on the rear of the receiver that tie to the stock are I think to reinforce the wood. Some of these are left off and the stock may break at the grip. Have seen it do this. Don't leave them off. So inspect the stock at the weak junction of the receiver and pistol grip for cracks. The stock was made in two pieces from the but plate forward and these are prone to seperate. Pin or glue if necessary. This is common.
    If you will coat the barrel and receiver(outside) and the stock with the old Johnsons past floor wax when it is all dry, you can deter rust and deteriation of the metal and wood. Of course all moving metal parts should be lubricated. I am an old fart. I still use lubriplate.
    Enjoy that scamp. I have and do. If all the above checks out you will have a weapon to enjoy.
    The 7.7 is slightly less a cartridge than the 06 but falls in the catagory of all the other military cartridges of that era.
    Sorry if I made this sound like a lecture but personally I like these weapons and have shot many of them.

    Much obliged eddie
  3. An interesting note, the Jap actions are one of the strongest out there. My gunsmithing instructor was telling us about tests trying to blow up differant military rifle actions. It seems they loaded the 7.7 to ungodly pressures and the only thing they managed to do was blow up the barrel. No matter what load they fired the action did not let go. Don't take this to belive that you can fire unsafe loads in your rifle, just an interesting piece of info.
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