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Primers coming out of pockets?

Discussion in 'Handloading and Reloading' started by David4516, Nov 12, 2012.

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  1. Walkalong

    Walkalong Moderator

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    Many folks with those old rifles size the case to fit their chamber, as in head spacing on the shoulder, just like many folks do with belted bottle neck cases. We have seen this talked about here a good bit. Some of those old rifles have so much head space that is the only way to safely shoot them, short of the expense of fixing the head space.
     
  2. brickeyee

    brickeyee Member

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    Reload to use the shoulder if you want the cases to last more than a very few loadings (sometimes even the first reloading causes failure).

    The original guns NEVER considered the idea of using the shells again.

    They used a generous headspace and chamber to make sure function was 100% even in poor conditions.
     
  3. Slamfire

    Slamfire Member

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    Don’t sweat it. Your loads are low pressure.

    About the first thing that happens when you ignite the primer is that the primer backs out of the pocket. Then the front of the case expands and grips the chamber walls. When pressure builds up the sidewalls stretch till the case head reaches the bolt face and stuffs the primer back in the pocket.

    I found this out when I started lubing my M1 Garand and M1a cases. Cases that were fired lubed the primers were nicely rounded. Cases that were dry the primers were flat. Obviously combustion pressures were the same but with the lubed cases the primer and the case moved to the bolt face at the same rate. With the dry cases the primers were flattened because they were stuffed back into the pocket under pressure.

    Now I do load development with lubed cases. When the primers finally flatten out I believe that I am really seeing high pressures instead of a false indication.

    Sometimes you will have low enough charges that the sidewalls do not stretch. This is an example of 150 gr SMK with 47.0 IMR 4895 in a 30-06. This is a service rifle equivalent load, probably lower 40 Kpsia in some rifles. In this rifle the primers backed out.
    150Sierra47-1.jpg

    150Sierra47.jpg
     
  4. RPRNY

    RPRNY Member

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    I just popped over from another Krag thread in which this came up. My opinion, FWIW: First, that amount of primer setback is not dangerous. It is not ideal, but the breech face on a Krag is not going to deform from it. While the underpressure and headspace issues referenced above are at play, the supposition that resizing is an issue for a rimmed case is, at best, nitpicking. A more likely issue, though related, is thin rim on the Remington brass combined with somewhat overly generous room on the rim relief.

    So, first, you need not be particularly concerned about the primer backing out slightly. On a straightwall case this is actually a good sign. In a bottleneck case, it suggests, as outlined above, a low, albeit not necessarily under, pressure load. You don't say whether these are cast or jacketed bullets. If jacketed, you can increase your charge of 3031 with 180 gr bulletr by increments up through say 38.5 grs well within safety parameters to see whether you get some case stretch that will stop the primer backing out. If you are going to IMR 4350 and a jacketed 220, again, up through 37.5 grs will be safe and sane (well below max of 40.5) and may address the issue as well. With cast, you really want the lower pressures and velocities so I stop at 36.5 of 4350 with the Lyman 311284 (210 gr) for example.

    Neck sizing only and slightly higher pressure may sort this issue out. If shooting jacketed, a good crimp like that from the LEE Factory Crimp Die will also help but I don't like nor do I counsel more than a light taper crimp for cast. I would also get some Winchester brass in. It's a little cheesy, admittedly, but the the rim size is .064 -.065 across two recent 50 ct bags I bought, which is SAAMI spec and just right for my Krag.
     
  5. David4516

    David4516 Member

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    RPRNY, thanks for the info. I didn't realize that the Remington Brass had a thinner rim than Winchester. I bought Remington brass because at the time it was the only brass I could find. I think they only do limited production runs for this caliber, so finding brass in stock of any brand is hit or miss.

    To answer your question, I'm going with Jacketed bullets, mainly Hornady. I have thought about cast but have not tried it. I'm a big fan of cast bullets for handguns, but rarely use them in rifles.
     
  6. RPRNY

    RPRNY Member

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    I can't say that the Remington brass is thin. You can check that, but if it is thin, I can say the Winchester brass I recently bought has correct rim thickness specs.

    In any event, with jacketed bullets, just up your charge incrementally to still below max and you will see the primer issue back off or disappear. Enjoy.
     
  7. ArchAngelCD

    ArchAngelCD Member

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    Just because a company lists data for a powder combination doesn't mean it's a good choice, safe yes, good choice, not always.

    If you look at all the 180gr bullet data you will see the velocities for H4350 are lower than other powders. That's telling me you can't get enough powder in the case to achieve the velocities the faster powders can. IMR4350 is showing higher velocities than H4350 but it's also a compressed load. Most powders perform better at the top of the pressure range and they for sure burn cleaner. While you CAN use H4350 safely the faster powders I listed above are much better choices.

    My favorite 30-06 powder is H4350 but when I load M1 Garand ammo I have to use a faster powder, usually 4895 or 4064. Sometimes you have to use something other than what you like because it will produce better ammo. but as always, you do what you think is best for you and your rifle.
     
  8. RPRNY

    RPRNY Member

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    AA may well make a point on the "faster" powders with jacketed bullets, although I am not an advocate for high velocity/pressure with the Krag.

    For cast, IMR and H 4350 are indeed good calls. I use 41.5 grs of H4350 under the Lyman 311284 210 gr gas checked bullet for 1870 fps. 40 grs with a jacketed 220 RN seems reasonable and appropriate, although I don't know the seating depth of that bullet, and 4350 delivers lower chamber pressures than the "faster" powders, which your Krag will appreciate.
     
  9. MEHavey

    MEHavey Member

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    +1

    It may headspace the first time on the rim, but after that size to headspace on the shoulder like any other bottleneck cartridge.

    (postscript: Same thing goes for belted magnum cases... resize to headspace on the shoulder after 1st firing)

    (postscript#2: In your case, at this time, the case has not stretched much at all. I'd up the charge enough to get re-seated/flush primers next time, and then size for the shoulder after that.)
     
  10. AABEN

    AABEN Member

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    Yes try 4350 it is a slower burning powder. I thank you might try some 8700. ACC load book 4350 39.6 up to 44.0 8700 47.7 up to 53.0 that would be a compressed load. GOOD LUCK
     
  11. gamestalker

    gamestalker member

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    That is caused from under pressure loads. When a load is too far below SAAMI pressures that will happen. It can also cause hot gases to leaks from the primer pocket which can damage the bolt face, gas cutting as it were.
    If you reduce that load any further you make experience a more serious problem known as secondary detonation, bad things happen.

    GS
     
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