Japanese 6.5
On 1-4-2003 I posted a query regarding the Chinese conversion of the Japanese 6.5 A reply posted by Darrel stated the caliber was 7.7. For clarity I consulted the book,Japanese Rifles of World War II by Duncan O McCollum to properly identify the Type of rifle used. The two conversions I have are Type 38 (6.5) with proper vertical markings and the two gas escape holes whereas Type 99 has only one gas escape hole atop the receiver and the markings for 99 run horizontal. All hardware of the barrels are those of Type 38 (6.5). It is my understanding many type rifles were converted to the 7.62x39 so possibly the 7.7 was also used. For anyone interested may this be of help.
Dr. J. Curtis Lane
Dr. J. Curtis Lane
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After WWII the Chinese Cummunist converted Japanese Arisaka 6.5 to shoot the Russian cartridge 7.62x39. Can any of you knowledgeable people advise exactly and specifically what proceedures were done to accomplish this. I note a spent 6.5 casing, which is slightly larger than 7.62 case, will still chamber in the conversion but bolt does not close. Thanks for any comments you may give. Very interested in how it was done.
Dr. J. Curtis Lane0 -
You are close. They converted the M-99's in 7.7 because the bore diameter was the same as the 7.62x39. all they had to do was set back the chamber a bit. I had one done and we even converted it to take an AK-47 mag which was not hard to do. Entire job cost me $90. What a riot to shoot and light on recoil. It got looks at the range as well. Gunsmith said it was an easy conversion. 0 -
I never heard of such a conversion or any 7.62x39 ammo showing up during the Korean War period. The US converted a bunch of the 7.7
Japs to 30-06 for use by the KSC in guarding ammo dumps. This shoots very well but is unsafe for more than 500 rounds when headspace goes out of spec.
In order to convert the 6.5 Jap to 7.62x39 you either have to rebore, rerifle and rechamber the original barrel or replace it. The 7.7 is a better candidate because it has a chrome bore.
The 7.62x39 conversion is a smarter idea for both the 6.5 and 7.7mm Jap because of lower chamber pressure. Adapting the AK magazine is an even better idea.
In spite of the novelty of such a conversion, you cant get over it being a cheap, doggy gun that doesn't justify much investment especially today with all the cheap surplus Mausers and the prospect of more Mausers flooding the market.0 -
I too had a 6.5 (Type 38) rifle that the Chinese had converted to 7.62 X 39. They had shortened the barrel and I guess had set it back as the barrel was the original Japanese one. They did nothing to the magazine and, consequently, I had trouble feeding the shorter round reliably. I noticed the bore was no longer chromed, so my thought's were that they had bored it out. Talking with Fred Hunnicut (author "Military Rifles of Japan") revealed that they had made these for the People's Militia and not the army circa middle 50's. 0 -
I appreciate all the input and I might add that yes, I could be mistaken about which caliber was used because after receiving the first reply I took a 7.62 round and inserted the bullet into the muzzle of the two converted rifles with ease. I also tried the bullet into the muzzle of a Japanese 7.7 and it fit seemingly the same in all rifles. The bore of the 7.7 being .08 m.m. larger than 7.62 could explain why the converted rifle does not shoot accurately. One of the conversions has the rear of floorplate cut off and a plug inserted and a cut made foward to the rails (?). One appears to have had a pin inserted to hold the barrel inplace for proper alignment. Both have barrels that appear original but about 4 inches shorter. Both conversions do not shoot accurately. Gentlemen, Thank you for taking your time to render your input and I hope more info will comeforth.
Dr. J. Curtis Lane0 -
diameter of a 7.62x39 is .311
The 7.7 jap is .311 a few might make .312
Most 6.5 Jap were converted to .257 Roberts
after the war.
some converted the 7.7 to .30-06 but not only
was it not accurate obviously but cases did buldge.
Anyone with a 7.7 Jap can get it going and shoot it
cheap if they reload OR convert it to 7.62x39.0 -
There's something other than the .001" difference between the 7.7 Jap and the 7.62x39 bullet that made for poor accuracy. It may have been the poor quality of the conversion and/or bad reboring and rerifling. As far as I know, the 6.5 Jap never had a chrome bore.
As far as the accuracy of the 7.7s that were US Arsenal converted to 30-06 goes, they were quite accurate. The chambering was uniform between them and bolts could be interchanged. In spite of the bore and and base differences they were quite accurate. I had a number of these in the far east and did further conversions on them like mounting the Army M82 scope with Redfield mount, bending bolts, cocking on opening and mounting a modified carbine muzzle brake. I liked to carry one on forays into the mountains because of their lightness and range.0 -
Attn:v35
Would you have any suggestions which might enable me to get better grouping or how I might check on the conversion as to how well it was done. I have read if the chamber is out of line to the bore and bolt face accuracy will be effected. I do not know how to check this. If the barrel is good,which it is,is it reasonable to believe the fault may be in the chamber? If so can it be improved? Can the trigger pull be made more desireable? What degree of accuracy might be expected,(grouping of 5 shots)? Your comments will be very welcome and thanks for your input. I have two of these rifles and naturally would like for them to shoot decent groups, whatever decent groups may be.
Dr. J. Curtis Lane0 -
Assessing chamber and bore conditions may be academic since you're limited in a remedy except for lapping of an uneven bore. You can make a chamber cast using lead/tin/bismuth low m.p. alloy. The length of cast should go beyond the throat to include uncut rifling. Measurements of base, shoulder, neck, throat dia and length, and the bore diameter can be taken.
Cut some shims from paper, aluminum foil or soda cans and with the firing pin and extractor removed, see how much you can stack up behind a cartridge before it starts to tighten up.
If it's more than .004" there's a headspace issue.
You can cast a lead lap or use a 32 cal lead bullet which can be mounted on a rod, lubricated and driven through the bore from the breech. You will be able to feel loose and tight spots, following which you coat the lap with valve grinding paste and work on the tight spots. The object is to get a uniform drag on the lap for the length of the bore except for the muzzle where it should feel tighter.
The mating surfaces of the striker and trigger sear are not parallel to the direction of travel of the trigger sear, resulting in camming back of the striker as the trigger is pulled. The reason for this is that when a trigger is pulled slightly and released the sear will cam back into full engagement. It also will resist jarring out of engagement and accidentally firing. Frictional drag between these surfaces can be reduced by carefully smoothening them with a Hard Arkansas stone. I have also altered the depth of sear engagement and sear & striker angles but would caution against it. Altering engagement must allow for looseness of the bolt in the receiver and the striker within the bolt or the gun could go off while working the bolt or the safety. Altering the angles beyond vertical is just as dangerous.
The best fix for the rough Japanese trigger is replacement with a Timney trigger if available.
If you find your chamber is oversize in neck diameter, throating diameter or depth there's no fix for the barrel.
Whatever the condition of the gun, a Timney trigger will improve the accuracy.0 -
Attention v35
Thank you very much for the wonderful specific information regarding the "conversion" Japanese rifle. I will do all your recomendations for which I am capable and wish I had communication with you direct. Very impressed with your information and thank you very much
Dr. J. Curtis Lane0 -
One other point about these rifle conversions to 7.62x39 is the Japanese rifling pitch which was proper for the 7.7mm military 173 grain bullet and probably too fast for the lighter 123 grain 7.62x39 Russian bullet.
If everything else is right with the rifle and accuracy isn't, the twist is likely to blame.0
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