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Thread: Over pressure signs when there wasnt any before

  1. #1
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    Over pressure signs when there wasnt any before

    I'm seeing the primers flatten out quite consistently on a 7mm RM load 162ELDX - 70gn of AR2217 fed215
    Have shot up to 71gn and not seen this before.

    Is this possible due to the cases being third firings and/or I push the shoulder back 0.02" to far?
    https://www.nzhuntingandshooting.co....ll-used-81123/

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    Edit think i goggled my answer
    "Often, a flattened primer indicates excessive headspace rather than high pressure. If a cartridge fits loosely in the chamber, the primer will flatten out when the case head slams back against the breech face during firing. This can happen even with low pressure loads. The primer brand can also have an effect on the amount of flattening. Federal primers are soft, and will flatten more than other brands with everything else being the same."


    Assume these are ok to fire and i should look for pressure signs in other places?
    Last edited by Vandros; 29-04-2022 at 11:47 AM.

  2. #2
    Caretaker stug's Avatar
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    Is it a new tin of 2217? Also we’re you able to check the velocity compared to previous loads?
    7mmsaum likes this.

  3. #3
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    Have you checked the case length?
    My 308 PPU cases from factory ammo needed trimming after their first firing.

  4. #4
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    powders 6months old, no speeds recorded as was hunting in the bush.

    Velocity will be down slightly as case will be expanding into chamber
    Last edited by Vandros; 29-04-2022 at 01:02 PM.

  5. #5
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    Flat primers is a sign to watch out for but not the most telling.
    What about other pressure signs ?
    how was the bolt lift after firing ?
    There does not appear to be ejector stamp mark or swipe marks on the case above.
    As @stug mentions above, are you seeing a change in muzzle velocity ?
    Have you weighed the brass to check how much variation between cases ? Some brands can vary quite a bit. Heavy cases = thick brass = less internal volume = more pressure for same load.
    T.FOYE likes this.

  6. #6
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    yes Case length is well within Saami Spec

  7. #7
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    Quote Originally Posted by chainsaw View Post
    Flat primers is a sign to watch out for but not the most telling.
    What about other pressure signs ?
    how was the bolt lift after firing ?
    There does not appear to be ejector stamp mark or swipe marks on the case above.
    As @stug mentions above, are you seeing a change in muzzle velocity ?
    Have you weighed the brass to check how much variation between cases ? Some brands can vary quite a bit. Heavy cases = thick brass = less internal volume = more pressure for same load.
    Absolutely no other signs on the cases, and they go in and come out fine.

    Interesting haven't weight the brass will try that next time round.

  8. #8
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    I had a similar problem a while back, turned out my 15 x fired brass, when running it through the full length sizing die, wasn't sizing properly any more. New brass was the fix for me.

  9. #9
    Member Mathias's Avatar
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    I think you will find belted magnums head space on the belt don't they? You may have loosened up your primer pockets a little if warm loads. They don't look too bad & no ejector stamp.
    chainsaw likes this.

  10. #10
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    I take it you mean 0.002”

  11. #11
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    A question- what length of time elapsed between you initially testing that load, then firing the "problem" ones?

  12. #12
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    Greetings @Vandros,
    Primer appearance has been continously debunked as a reliable means of guessing pressure. There are just too many variables to lead you astray. Much more useful is velocity and I test each new lot of powder, for velocity, against the last pror to loading with it. Usually there will be a small difference but sometimes a larger one and rarely a much larger one so don't do this with a full load and make sure that your loads are identicals except for the powder and shot in the same session. Your load is max under the Hodgdon data but this has been dialled back considerably over recent years in the 7mm Rem Mag to allow for pressure variations. Much more likely IMHO is that the difference yoy noted is due to slightly more headspace. You don't asy how you are setting and measuring your shoulder bump but a lot of methods for case sizing to achieve this can have different results each time you set them up. Belted cases need careful sizing to fit the chamber as they mostly do not headspace on the belt.
    In short stop worrying about primer appearance but do check velocity with new batches of loads and definitely do not ignore an ejector stamp or rub mark. The latter needs an immediate reduction in load.
    Regards Grandpamac.

  13. #13
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    Primers dont mean much for pressure signs. And you'll get a rub mark from sizing your cases as little as possible. The main thing to consider is velocity from a chronograph that you trust (check it against .22 LR velocities) If you are getting velocities higher than book then you are getting higher pressures.
    Last edited by JohnDuxbury; 30-04-2022 at 10:05 AM.

 

 

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