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Primer flow on light loads

Discussion in 'Handloading and Reloading' started by Lee Q. Loader, Jan 12, 2019.

  1. Lee Q. Loader

    Lee Q. Loader Member

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    Pic is brass I just shot in my Ruger 9e. The exact load was 5.3 grains of Unique under Berrys 115 plated RN. Oal 1.125 using all Aguila brass. The loads had very little recoil and the brass was only flying a few feet.
    So why do the primers look like that?
     

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  2. 25-20 WCF

    25-20 WCF Member

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    An oversize firing pin hole in the breechblock can cause this.
     
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  3. fxvr5

    fxvr5 Member

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    Look at the breech face of your pistol. Is the firing pin hole a bit dished out? Some guns have odd firing pin holes. Glock fired cases have a rectangular imprint in the primer, Berettas have a circular bump on the primer, similar to yours, and so on.
     
  4. troy fairweather

    troy fairweather Member

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    is it the first time using this primer in the gun.
     
  5. 2ndtimer

    2ndtimer Member

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    My Remington 700 SPS Varmint in .223 Rem. has done that since new, with factory ammo and handloads of all levels. Oversized firing pin aperture or undersized firing pin. It has been doing it for 10 years, without serious issues. Had I sent the rifle back to Reminton when new, they probably would have kept it a few weeks, test fired it and returned it, saying it was within factory spec.
     
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  6. Lee Q. Loader

    Lee Q. Loader Member

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    No. It's weird because I load quite a bit heavier that this and haven't noticed primers like that. I always use CCI 500 primers.
     
  7. troy fairweather

    troy fairweather Member

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    hum your crim should be light because the 9mm. have u checked the chamber for a ring of brass in the throat.
     
  8. Englishmn
    • Contributing Member

    Englishmn Member

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    Those are fine.
    Overpressure will flatten the rounded edge of the primer flush with the pocket. IMG_20190112_210831.jpg
    This pic is fairly high pressure it engraved the primer but not so high it flattened out the rounded outside edge of the primer.
    It's from my bad case collection.
     
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  9. joneb

    joneb Member

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    What primer are using
    O
    I always use CCI 500 primers.
    sorry
    I have funky primer strikes with light loads in a Sig P938, they look just like yours.
     
    Last edited: Jan 12, 2019
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  10. Slamfire

    Slamfire Member

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    As 25-20 said, it most likely is due to an over sized firing pin hole. As to the guy with the Remington, maybe it was a decade ago, a fellow at the range had an new Remington M700 that was showing primer cupping around the firing pin hole. He claimed he talked to the factory and that it was deliberate, that is Remington made the firing pin hole large so the primer would cup around the firing pin, and make a better gas block! Hey, could be.

    Auto pistols and auto guns are very hard to diagnose in terms of over pressure. Unlike manually operated arms, where you will feel sticky extraction, these things open up on their own. Primers are only a reliable guide to high pressure when they blow, or pierce. And if they do that, you are way over maximum pressure. Just this week I was shooting my JC Model 50 in 30-06 and every one of the loads blew, or had gas leak around the primer, and all of the cases had expanded primer pockets. And yet, no primer cupping! While the primer edges looked flattened, but not perfectly flat, the firing pin indentation looked normal. However, the blown primers were a clue something was wrong.

    For an auto pistol, if you pistol extracts and feeds normally, your ammunition is probably safe pressure wise. Over pressure ammunition will over accelerate the mechanism and you will have unusual function problems. A typical one is an over ride where the slide closes on an empty. The slide was accelerated so fast that the next round in the stack was not picked up. Might have stove pipes, or cartridge jammed on the feed ramp. With my 1911's, the ejection distance gets to be around 20 feet. I much prefer the brass falling within bending distance, not walking distance.

    Those fun loving guys at AMERC pushed out a lot of junk ammunition, and got rich doing it! You can see the after effects of overpressure

    renYr8v.jpg

    This is a picture of the AMERC cartridge which caused this mess. Excessive pressure caused the unsupported part of the case head to deform. The one which the sidewall ruptured caused all the breakage. I want to make the point, the cartridge case is a gas seal. It is not a structural element, it is not there to carry load. It is infact, very weak. The locking mechanism, barrel, chamber, are all there to support the case. A cartridge case cannot hold all the pressure by itself, and the unsupported areas will rupture given enough pressure.

    HEP0oHT.jpg

    Clearly overpressure cartridges. This first is a 9mm

    ayF5ybM.jpg

    Another example

    RFAV9pG.jpg
     
  11. ArchAngelCD

    ArchAngelCD Member

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    There is nothing wrong with those primers. You said yourself the cases are only being thrown a short distance.
     
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  12. drband

    drband Member

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    ^^^^This^^^^
    Lots of manufacturers seem to chamfer the firing pin hole in the breechface resulting in what you see. It’s not a problem.
     
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  13. Rule3

    Rule3 Member

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    Little to nothing about pressure can be told by primers in 9mm handgun loads. Like reading Tea Leaves

    Shoot some factory ammo and see what the primers look like,
     
  14. Lee Q. Loader

    Lee Q. Loader Member

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    Thanks everyone for the responses. So glad to have this website for the wealth of knowledge and reassurance that my loads are OK.
     
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  15. Texas10mm

    Texas10mm Member

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    By the time one sees the traditional high pressure signs in most pistol brass you're very deep into danger territory.
     
  16. Laphroaig

    Laphroaig Member

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    My Beretta 92FS makes a primer strike almost exactly the same as the OP's. Very distinctive and I can always tell my brass from the others because of it.
     
  17. D Rock

    D Rock Member

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    Like others have mentioned, different pistols can show distinctive markings.
    fMKxJYn.jpg

    One thing I would check based on the pictures is if your pistol is going back fully into battery. Could just be the picture angle, but the FP marks look quite a bit off center. Most pistols will still fire if only slightly out of battery.

    Dave
     
  18. PapaG

    PapaG Member

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    One other possibility is that the primer is backing out a little due to too little pressure and then under recoil the case is struck back against the slide reseating the primer causing the funny ring. Doesn't take much headspace for this to happen. Used to see it all the time with lead bullet target loads in several centerfire rifles. (Which also pushed the shoulders back negating them for full power loads later, not a problem for your straight wall stuff.)
     
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