6.5 Jap Type T-38 PROBLEM

Discussion in 'Curio & Relic Discussion' started by TXnorton, Feb 7, 2010.

  1. TXnorton

    TXnorton New Member

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    I finally had a chance to take the new (to me) 6.5mm Jap Type 38 out to the range. However, all did not go well.

    I shot 5 rounds, then had five consecutive non-fires.

    All fired rounds had backed-out primers.

    All non-fires had light firing pin impressions.

    The ammo is Hornady 6.5 JAP. The head stamp is nny, 6.5 x 51R. My Hornady Loading Manual indicates the 6.5 Jap is 6.5 x 50mm.

    I brought everything home, and then completely stripped the bolt and gave it a significant cleaning. It had a lot of old powder residue inside the bolt body where the striker pin resides. I suspect this was the cause of the non-fires.

    I then pulled the bullets and powder from 5 other new bullets, and then fired them (primers only) in the garage. These fired well, with good firing pin impressions, but the primers were also backed out.

    I then re-sized these cases in a new Lee sizing die, and re-primed them. They also fired well (primers only) with good pin impressions, but also had backed-out primers.

    I checked the dimensions on the cases of all five rounds that successfully fired at the range. All dimensions seemed to be in spec, and I saw no bulges or increased diameters at the case head.

    Attached are four photos. The first shows the non-fires (top row with light pin impressions) and the fired rounds are on the lower row.

    The second photo shows a closer shot of the non-fires.

    The third photo shows the backed out primers on the rounds actually fired at the range.

    The fourth photo is the five cases after re-sizing the brass then firing in the garage. Note the primers are still backed out.

    Is this a case of excess head space and would another bolt possibly solve this problem?
     

    Attached Files:

    Last edited: Feb 7, 2010
  2. c3shooter

    c3shooter Administrator Staff Member

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    Get thee to a gunsmith- thou hast a headspace problem! ;)

    Fix may not be a new bolt- it MAY be setting the barrel back one thread. Also have chamber checked- roughness, etc.
     

  3. jpattersonnh

    jpattersonnh Active Member

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    It is a controlled feed. Check and see if the firing pin hole in the bolt is oversized. Is the cartridge jumping off?
    When you fire a live cartridge and resize, are you full length or neck sizing. If you are full length you could be pushing the shoulder to far back. Try neck sizing. Jap rifles are known for roomy chambers. Your ammo is Prvi Partizan(nny). Try Norma.
    My Igman and Prvi 6.5x55 ammo both have issues. They are hard to chamber. The brass/neck is to long.
     
    Last edited: Feb 7, 2010
  4. redarmyman

    redarmyman New Member

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    You won't believe it but this recently happened to me! To make a long story short - 6.5 Jap is not supossed to be rimmed (or so my gun smith tells me). In my case, the bolt would not close and I didn't try to force it. I ordered from another source, but they are on back order and have not arrived yet. They came in a Hornady box. I can't put my hands on them right now but I'll dig for them and see if the bottoms say the same as yours. Where did you order yours from?
     
  5. ronl

    ronl New Member

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    The 6.5 Jap cartridge is of the semi-rimmed variety. First I would check for possible head case expansion using the old paper clip tool. If you do not feel a bump inside then I would check to see that the case chambers correctly then resize using those dimensions. You could also measure case length before and after firing. You could also make a chamber casting and check the dimensions. Most of these rifles have seen much service in some of the harshest environments on earth. Most are very worn. They were used through the Korean war and into the Indochina war. The example I have was used so much that the follower has worn to the point where the bolt will close on an empty magazine. That's a lot of rounds down the pipe.
     
  6. TXnorton

    TXnorton New Member

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    First - Thanks for all of the repsonses:

    C3 - I looked at the barrel to reciver fit up and it looks like the barrel is fully home against the receiver crown.

    You may be able to see this in the photos I originally posted when I bought the gun.

    http://www.firearmstalk.com/forums/f37/type-38-6-5-jap-22541/

    I cannot see how the barrel could be screwed in another turn. But I am not a gunsmith, so I do not know how this could be done.

    JP - The firing pin hole seems correctly sized, I think that the mis-fires were due to a build up of carbon and powder residue that may have built up inside of the bolt that may have loosened up when I fired the first 5 rounds and the residue may have kept the striker from travelling fully forward. The inside of the bolt probably had not cleaned in many years. It was filthy! After I cleaned the bolt, the rifle did fire 10 (primer only) rounds and left good impressions in the primers (although the primers were backed-out). I did full length re-size the brass to see if there were any dimensional differences, but I could not measure any discernable dimensional changes between the new unfired brass, once fired brass, or the re-sized brass. The brass cases all measure very close to the specs shown in my Hornady reloading manual

    RonL - The rifling on this T38 is is somewhat worn, but not too bad. The bolt WILL close on an empty magazine. When I first bought the rifle I ran few patches down the bore to clean it before firing. It seemed clean after about 4 patches. After I fired the 5 rounds at the range I cleaned it again this time with vigourous brushing and MANY patches As seems to be typical for several of my old milsurps, there seemed to be no end to the cleaning process. I supsect the firing of live ammo heated up the barrel and allowed some of the old residue to be more readily removed.

    So, I am still not sure what to do. I guess I will take it to a gunsmith, but I am not sure what he could do. In the end I have $200 invested in the rifle, plus $100 for a nice bayonet, $140 in ammo, $30 in 6.5mm bullets and $40 in reloading dies. Maybe I have an expensive wall hanger?
     
  7. ronl

    ronl New Member

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    Since you want to shoot it occassionally, and you reload, then simply load light loads for it and keep a check on the cases. If the headspace is excessive, then you may get only two-three loadings before you have to throw the cases away, but you still can shoot it. If it looks at all that headspace separation may occur with any casing, toss it;period. I wouldn't spend much money at a gunsmith on the rifle because the value of it just doesn't warrant it. Just be very careful with the loads and the cases and have a go at it. The T-38 action is the strongest military mauser type there is. Just resize so the cases fit properly; barely snug upon closing bolt. It could possibly be that the lot of ammo you shot had the primer pockets cut slightly too large; small chance, but possible. I'd also check before and after case lengths and that will give you an indication if it is a headspace issue.
     
  8. TheOldMan

    TheOldMan New Member

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    I'm in agreement.. It may be my eyes but it appears that the cases are also slightly bulged on the rounds that you fired at the range with the popped primers? Also, the fella that mentions the primer pockets being a bit large.. Not that it happens often but it could be a contributing factor.

    Btw, I looked at your thread with the rifle photos.. Very nice find. Headspacing this rifle would not be that expensive and getting the once over by a qualified gunsmith does seem to be the prudent way to go (imo)
     
  9. TXnorton

    TXnorton New Member

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    Ron and OldMan: Thanks for the input.

    Yes, I'd like to keep this rifle as an occasional shooter. This rifle has seen lots of use, judging by the condition of the rifling (somewhat worn) and the amount of powder residue I am cleaning out of the bore. The bolt has a matching serial number to the rifle, so it would appear that this is how it was shot in its previous life.

    In for a penny, in for a pound, so I found a T-38 complete bolt asssembly at Numrich for $80. So I bought it to see if this makes any difference. I'll try that and see if the primer backing out problem looks any different.

    I'll check the primer pockets with my primer pocket swager and see if they seem too loose. If they are not very tight, would primer sealer do anything beneficial?

    I do not pretend to understand all aspects of the head spacing issue, but I am trying to learn more about this subject. What exactly would a gunsmith do to this rifle in order to correct an excessive headspace problem?
     
  10. ronl

    ronl New Member

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    What powder and how much are you using? Upon firing, primers will initially back out then are shoved back into the pocket by pressure. If you are using very light loads you may not be developing enough pressure to reseat primers. I pulled my T-38 out and looked it over very carefully. (never fired) I do not know how headspace is measured in a semi-rimmed case. On a rimmed case it is measured from bolt fact to cut out for rim. You may well be on the right track with a new bolt. Another thing is to make sure your bolt head is not one from a T99. Probably not, but just tossing things out there. If you have a T99 just compare bolt heads and it is easy to tell. The main thing is that as long as you are not pushing the cases too hard (make a paper clip tool and use it) and are not creating the bright shiny ring that indicates impending head separation, you will be okay. The process for reducing excessive headspace is to remove the barrel, cut new thread(s) on barrel with the proper timing. recut extractor groove to proper depth, recut chamber.
     
  11. TheOldMan

    TheOldMan New Member

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    To eliminate any confusion

    I should have posted that "checking" the headspacing would not be expensive. As posted above, correcting the problem may be more than you are wanting to spend. But as you posted, "in for a penny, in for a pound". I'm very interested to follow this one out and see what you find.
     
  12. TXnorton

    TXnorton New Member

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    TheOldMan:

    The ammo is new Hornady 6.5 Jap. As noted in my first post the brass is headstamped nny 6.5 x 51R, but the brass measures almost exactly per the dimensions shown in the Hornaday reloading manual. The 6.5 Jap is actually a semi-rimmed round.

    I have pulled the bullets and dumped the powder from 10 rounds so far to test primer firing and firing pin impressions after I cleaned the inside of the bolt.

    The amount of powder recovered seems to be about 23-24 grains per cartridge. Of course I do not know what kind of powder this would be. I had planned on reloading with IMR-3031 (because I already have that powder) and would have used +/- 30 grains.

    I have read up a bit on headspace and what happens in the chamber during the firing of a rimless round, and I was on the track of thinking that the Hornady rounds were loaded so lightly so as not to re-seat the primers in the firing process.

    Last night I did an experiment. I installed an unfired case in the chamber with a bit of soft waxy material (actually a bit of SPG BP bullet lube) stuck on the case head over the primer. I then removed the extractor from the bolt and ran the bolt fully home in the chamber. I then extracted the bolt and case and measured the thickness of the (now compressed and flattened) SPG wad. I did this twice and ended up with readings of .032" -.042". I repeated the exercise with a case that had actually been fired and not re-sized. This SPG wad measured about .024" thick.

    So this tells me what? That the headspace with new brass is excessive at .032" - .042" That the once fired brass has been somewhat fire-formed to have stretched the case a bit to reduce the headspace by approximately .013"?

    I was hoping to see if the once fired brass would have fire formed to lengthen the case shoulder dimension to eliminate the headspace. If it did, then I was going to pursue just neck sizing the once fired brass. But I did not see that much of a difference in the headspace between the unfired and once fired cases. Maybe, if the factory rounds were loaded to very low pressure levels, then a higher pressure load would more fully fire-form the brass to fit the chamber?

    Now at this point I am WAY beyond my level of competency on this subject, so I'll be calling a local gunsmith today and talking about what he may be able to do.
     
  13. TheOldMan

    TheOldMan New Member

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    Very clever way of checking the headspacing. According to what you've found out so far, it sure looks like you've found your problem. I'd never heard that primers would buldge and retract as was mentioned in a prior posting. The more I thought about it though, it kind of makes sense that it could happen.

    Learned something new today... Thank you sir.
     
  14. ronl

    ronl New Member

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    I agree with The Old Man that you've probably found the problem, that is if semi-rimmed headspace is measured the same as rimless, which I expect it is. Good luck with the old rifle there and keep us up to date on what's going on.
     
  15. c3shooter

    c3shooter Administrator Staff Member

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    As Ron said- smith removes barrel, cuts shoulder of barrel on lathe, adds thread, so that when replaced, screws in further. DO check inside the brass- also check chamber for roughness/pitting, etc. Those rifles got used hard, put up wet, tough climate, corrosive primers, etc. Something is keeping it from reseating primers.
     
  16. TXnorton

    TXnorton New Member

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    Thanks C3 and ronl (somehow I missed reading the last part of Ron's prior post). Now I understand what the gunsmith will have to do, I'll be checking this out next week!
     
  17. Sport45

    Sport45 New Member

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    Have a 'smith check the chamber. At some point in its life this rifle may have been re-chambered for 6.5/.257 Roberts. That was a popular conversion many years ago.