Just Right Carbine explosion

Discussion in 'Rifle Country' started by MySuomi, Oct 12, 2020.

  1. MySuomi

    MySuomi Member

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    I need some help determining what went wrong. Here is the background. I have had a 9mm JRC for about 8 years. Has worked flawlessly and has been a joy to shoot. I was able to get the 40 cal conversion kit direct from JRC

    and installed it last week. I took it out to the farm to shoot. Ran 3 rounds thru it before it went bang. I have lots of pictures so I will post those next.
    • The first round fired but did not sound right. Naturally I did not let that stop me.
    • The second round fired and still did not sound right. Lot's of smoke. I said, ok one more just to see. (This was stupid. I should have stopped).
    • The third round blew the magazine out of the magwell, cracked the bolt, blew the hole bottom off the round and stuck the remainder in the throat of the barrel. The receiver seemed fine after inspection as did the barrel.
    • I found the fired casing from the second shot. It shows pressure signs with the primer bulged out.
    • I was shooting Remington 180 grain FMJ. I had shot some of the same box last week in my Sig239 and they shot fine.
    I will contact JRC today. But, I am not blaming them. I just want to know how I screwed up the conversion. I never want to do that again.
    IMG_2104.JPG IMG_2105.JPG IMG_2107.JPG IMG_2108.JPG IMG_2109.JPG IMG_2110.JPG
     
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  2. 1KPerDay

    1KPerDay Member

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    OOB? Short chamber holding the bolt open maybe?
     
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  3. MySuomi

    MySuomi Member

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    Here are some more pictures. Note the bulged out primer in the fired case.
    IMG_2099.JPG IMG_2114.JPG IMG_2115.JPG IMG_2116.JPG IMG_2117.JPG IMG_2119.JPG IMG_2120.JPG
     
  4. MySuomi

    MySuomi Member

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    Maybe. But, when i was function testing, the rounds all seemed to seat and the bolt seemed to be closing fully.

    I did notice that the next round up in the magazine had the bullet jammed deep into the casing. I was wondering if some how the bullet was getting pushed into the casing as the round was loading. Thereby causing a pressure situation.
    The round in the middle was the next round up in the mag. The one of the left was the second one. The one on the right is the spent round from the second shot. It has the bulged out primer. IMG_2100.JPG
     
  5. jmorris

    jmorris Member

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    Anything remain in the chamber and/or barrel now?
     
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  6. denster

    denster Member

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    Short chamber is a possibility but not probable. More likely improper headspace when installing the barrel that allows the extractor to hold the round against the breechface but when the bolt is fully forward the round is not completely chambered.
     
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  7. jmorris

    jmorris Member

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    Ah, #4 would do it.

    Setback can cause destruction for sure. Speer has wrote about some combinations that seated just .030” deeper more than doubled pressures.

    AE128D3F-4109-4C4C-A942-756320F81755.jpeg

    CCI aluminum cases are ones I avoid too.

     
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  8. MySuomi

    MySuomi Member

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    Once I removed the blown up case there was not anything else in the barrel. The case was not even stuck. I was able to pull it out with needle nose pliers.
     
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  9. Ru4real

    Ru4real Member

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    Nice photos. Two questions.
    Is this factory ammunition? It looks like it was Remington factory ammo.
    Is something missing from the bolt face?

    The photo of the case in the stuck chamber shows it is probably seated correctly and the bolt was closed when fired. Note the interior & exterior case taper in relation to the end of the barrel/chamber and the extractor mark on the side of the case. Also, the top of the case head blew out, the bottom of the case head directed gasses down the feed ramp towards the nose of the next bullet in the mag setting it back.

    The photo of the receiver shows there is no gas port. If there is no gas port, that is strike one.
    The photo of the bolt face shows the the case head is not supported on the top of the case, by design (if something’s not missing). Strike 2.
    The photo of the set back round shows gasses pushed it back. That was strike three for your third round fired.

    Your first round may have set back and compromised (crack) the case on the second round which may be why it was smokey - insufficient pressure. The second round set back the third round. And the third round set back the fourth, sitting in the mag when the gun came apart.

    Thank goodness you weren’t seriously hurt.

    View attachment 948238 View attachment 948239 View attachment 948240
     
    Last edited: Oct 12, 2020
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  10. MySuomi

    MySuomi Member

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    Yes, it was factory ammo. And i don't think anything else is missing from the bolt. When I get home from work I will compare the cracked bolt to the original 9mm bolt.

    This could have been much worse. I was stunned for a few seconds after the "explosion". Then I counted all of my fingers. :)
     
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  11. wiscoaster

    wiscoaster Member

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    Glad to hear you're OK. Even more glad to hear a good lesson was learned. Kudos to you.
     
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  12. murf

    murf Member

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    take a "good" round and try to push the bullet down into the case. use a table or counter top and push with your hand. you may have some bad rounds.

    luck,

    murf
     
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  13. Jerry M

    Jerry M Member

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    Check the barrel closely for a bulge. is it possible that the two shots that didn't sound right were squibs and the third shot cleared the obstructions (with great pressure).
     
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  14. mgmorden

    mgmorden Member

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    The round looks fully seated, and out of battery isn't nearly as catastrophic on a blow-back action vs a locked breach.

    Given that the first two rounds sounded weird, SOMETHING was already up. I'd wager that they were either squibs or severly underloaded. One or both of them likely lodged in the barrel. When the third (full power) round went off it likely pushed the barrel clean but with enough back-pressure to rupture the case.

    As Jerry M said, I'd check carefully for a bulge in the barrel. If there are none I'd personally try again with a single round, make sure it sounds ok and remove the upper afterwards to ensure that it cleared the barrel.
     
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  15. 792mauser

    792mauser Member

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    Sounded funny = (usually) squib-ish load.

    Had something like happen in an Uzi. Round sounded funny, fired next shot before realizing it. BOOM! Bulged the barrel and nothing more thankfully.

    Seen 38 spcl 110gr projectiles lodged in the forcing cone by just a primer.
    Then the idiot decided to shoot it out, and cracked & bulged the barrel and frame.
     
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  16. Taurus 617 CCW

    Taurus 617 CCW Member

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    Another thing to look at is headspace as others have mentioned. The headspace for that round is based on OAL for the cartridge. Double check your barrel marking to make sure they didn’t give you a 10mm by mistake or anything else funny. It sounds to me like there was something wrong from the get go indicating that the condition never changed. My suspicion is the relationship between the bolt snd barrel.
     
  17. MySuomi

    MySuomi Member

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    I will investigate the barrel more fully tonight. More pictures as well. I don't think it was a squib though. Especially since the second round fired shows a bulged primer. But, i could be thinking about this wrong.
     
  18. denster

    denster Member

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    I still believe headspace is the problem. Did they give you instructions for headspacing the barrel when you did the caliber change?
     
  19. marksman13

    marksman13 Member

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    Squib round on the first shot? By sounded funny do you mean it sounded weak?
     
  20. whughett

    whughett Member

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    My monies on a headspace problem and the fact the gun will fire in that condition. Aren’t these short, mouth head spaced cartridges like 9s and 40s big on case bulging at the base any way?

    At any rate if it don’t sound right it usually I ain’t. A prudent shooter stops right there.
     
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  21. Big Bore 44

    Big Bore 44 Member

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    Just a question about the conversion kit. Did the mfg include a new recoil spring? The cases may be blowing out due to the bolt moving early.
     
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  22. 243winxb

    243winxb Member

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    Blow back action opened to soon, will show high pressure signs as the round is still in the process of firing. Brass not supported. 35,000 PSI got loose. Blow back actions at this PSI, not a great idea. Imo.

    The added smoke and odd sound on firing goes with the action opening too soon. Brass not stuck in barrel, shows no over pressure factory ammo as cause.

    Out of Battery firing- The disconnector should keep the gun from firing if the round is not full chambered.

    The round that kaboomed was not fully in the chamber , at peak pressure, for some reason?

    https://www.thehighroad.org/index.php?threads/hipoint-40s-w-carbine-kaboom.773546/
     
    Last edited: Oct 12, 2020
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  23. film495

    film495 Member

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    you're so lucky you didn't have a squib load stuck in your barrel. if something isn't right or feels really odd, firing again is a wicked mistake, unless someone is shooting back at you and it is the lesser of 2 evils.
     
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  24. WestKentucky

    WestKentucky Member

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    Did the funny sounding rounds work the guns action?
     
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  25. Alex Clayton

    Alex Clayton Member

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    I have a few of the TNW's which from the outside look like the same rifle. Did the conversion just include a new bolt head? If so did it say anything about the buffer spring? It sure looks to me like as others mentioned the action is opening too soon. So not enough weight between the bolt, and the buffer spring combo. This is assuming the JR is the same internally as the TNW's. I can shoot 9mm, .45, and 10mm through mine with just different bolt heads but I have never seen the internals on the JR to see if they work the same. ??
     
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