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Thread: Had a kaboom with my reloads.

  1. #21
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    Quote Originally Posted by Blanksguy View Post
    After looking at your case photos...Ö.what I am seeing (due to the flow of the brass) is "over-pressure" due most likely to bullet "set-back" during chambering. This bullet set-back would make your chamber-pressure increase dramatically.
    I've found this not to be as significant of an issue as I had previously thought.

    When I first tried loading 77 gr Sierra TMKs, I loaded to small batches of OTMs and TMKs to compare. Both had identical charges. The TMKs have a much different ogive and required the bullet to be set much farther into the case than the OTMs to achieve the same over all length. When we chrono'd the loads, they shot the same velocity.

    Now if the round was really deformed with the bullet mangled somehow, yet still able to chamber... perhaps it could be the cause. But a 55 gr fmj set back simple doesn't take up anywhere near the case volume that a 77 gr does at correct over all length.

    And then of course with more "jump" to the lands, you get more initial bleed of, and thus LESS pressure spike. I just don't see set back as a realistic cause of this.
    "You people have too much time on your hands." - scottryan

  2. #22
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    Were the cases measured to make sure they did not exceed maximum length? Were they trimmed prior to reloading? How much crimp do you adjust your dies for, .002", .003"? If the case length is excessive, the amount of crimp can increase when the bolt goes into full battery and the case mouth is forced into the chamber.

    Some will disagree, but I believe the hammer will drive a bolt into full battery if the bolt is open a few thousandths of an inch due to lack of full length sizing or excessive case length. With the bolt in full battery, I've had case head separation on well worn brass when shooting match loads through a lightly used barrel and did not experience an overpressure failure like you experienced.

    There is no indication of minimum recommended charge weight on the Alliant website. How did you decide on 23.0g of AR Comp? I've never used AR Comp and have no experience with it.
    Train 2 Win

  3. #23
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    If the hammer drives the bolt forward, isn't the bolt then properly locked as needed to let the bolt carrier sit close enough the firing pin can reach the primer? Asking honestly.

  4. #24
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    Case trim length is another thing I've found NOT to be a big issue. Black Hills old Remanufactured 55 gr ammo used to have massively over-length brass. And people shot that stuff by the 10s of thousands of rounds and swore by it.
    "You people have too much time on your hands." - scottryan

  5. #25
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    Quote Originally Posted by taekwondopreacher View Post
    If the hammer drives the bolt forward, isn't the bolt then properly locked as needed to let the bolt carrier sit close enough the firing pin can reach the primer? Asking honestly.
    Yes. Out of battery notion is waste of discussion. Not the cause. (as Mk18pilot pointed out a few years back... without the bolt locked, you don't achieve the over 65,000 psi or whatever needed to burst the case head)
    Last edited by markm; 12-06-19 at 14:51.
    "You people have too much time on your hands." - scottryan

  6. #26
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    Quote Originally Posted by T2C View Post
    There is no indication of minimum recommended charge weight on the Alliant website. How did you decide on 23.0g of AR Comp? I've never used AR Comp and have no experience with it.
    Not the OP, but...

    On the website, right before you enter the guide:
    REDUCE RIFLE AND HANDGUN CHARGE WEIGHTS BY 10% TO ESTABLISH A STARTING LOAD

    My math gives me 23.04 gr for a starting load.

  7. #27
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    Quote Originally Posted by Chubbs103 View Post
    Not the OP, but...

    On the website, right before you enter the guide:
    REDUCE RIFLE AND HANDGUN CHARGE WEIGHTS BY 10% TO ESTABLISH A STARTING LOAD

    My math gives me 23.04 gr for a starting load.
    Valid point. I like to see data that displays the recommended minimum charge weight in grains. I have been on the telephone with Hodgdon a few times and was told that listed minimum charge weights were actually tested.
    Train 2 Win

  8. #28
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    Quote Originally Posted by markm View Post
    Case trim length is another thing I've found NOT to be a big issue. Black Hills old Remanufactured 55 gr ammo used to have massively over-length brass. And people shot that stuff by the 10s of thousands of rounds and swore by it.
    I was not aware that Black Hills brass was overlength; thanks for the information. I have not measured .223 brass on a loaded cartridge, then fired ammunition with overlength brass out of a rifle. I have seen what out of spec brass will do to a M1 Carbine. The M1 Carbine brass was on ammunition that I culled out of new factory ammunition and was over maximum length by .002" - .004". Another shooter on the firing line did not think it was an issue and asked to fire it. I should not have given him the ammunition. During the slow fire prone stage he blew up his Quality Hardware carbine and I was hit with a piece of the stock. I know the chamber was within service limits, because I watched him check with Go and No Go gauges when he bought the carbine several weeks before the incident. The bolt did not go into full battery on the No Go gauge.

    When it comes to overlength brass on bottle neck cartridges, I defer to the Hornady Handbook of Cartridge Reloading, Fourth Edition, Vol. 1, page 11. Hornady cautions against reloading overlength brass, due to overpressure concerns. On a service rifle with a generous cut on the leade, or worn throat, it is less likely to happen, but still possible.

    One thing I know for certain is that I can't be certain what will happen if I don't trim or full length size brass when reloading for a semi-automatic rifle.
    Last edited by T2C; 12-06-19 at 15:22.
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  9. #29
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    Quote Originally Posted by CAMagnussen View Post
    I've seen enough "kabooms" with reloads to know I have no interest in them. Good luck. Glad you were not killed, blinded, or otherwise. Is it really worth your while to reload 5.56 cartridges?
    Iíve seen enough kabooms with factory ammo to know I have no interest in them.


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  10. #30
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    I think I know where I errored. I must have loaded 5.56 cases using 223 load data. It still should be under max, but a 556 barrel, hot day and maybe factor in bullet set back.

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