normal primer or overpressure?

Discussion in 'Reloading' started by crittrgittr, Jan 10, 2014.

  1. crittrgittr

    crittrgittr Well-Known Member

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    I have heard a lot about flat primers when you over pressure a load. Could someone please post some pics of an overpressured primer. almost all my spent primers look the same, so I don't think Im having an issure but would like to see some to make sure. Thank you
     
  2. Barrelnut

    Barrelnut Well-Known Member

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    Kind of hard to tell just by the looking of the primer if there is a pressure problem. Reason is different primers have different hardness and thickness of the primer case. For example CCI primers have a thicker case than Federal primers.

    For pressure signs, I look at the head of the case itself. If the case it slamming against the bolt face so hard that it is causing the ejector to leave a shiny little ring on the case head, I call it quits and back off some. Also if the bolt is suddenly harder to lift cause the case has expanded so much in the chamber during the firing.

    So usually look at all three of these things: primer flatness, ejector marks, bolt lift and decide when to start backing off.

    Another good sign is when you seat the new primer and the primer pocket is suddenly real loose is another good sign that pressures are getting too high.

    How about sending us some pics of your case heads with primers and we look at those. :)
     
  3. Broz

    Broz Well-Known Member

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    It is true some primers are harder than others. But I feel a first sign of pressure is to punch the spent primer out of the case. If it has a muffin top you are approaching high pressure. Then as stated soon after is usually the stamp of the ejector pin hole on the head.

    Jeff
     
  4. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Primers are about like reading tarot cards. Headspace has more to do with primer flattening than pressure generated. Also, remingtons are known for sloppy firing pin fit, so you'll see a bit of cratering in some rem's when you get above start loads. That said, if you watch from a known mild load you will see some distress signs as the loads get hot. You won't likely blow a primer or loosen a pocket until you are way to dang hot though.
    Broz and Barrelnut have pretty much hit the nail on the head on this one.
     
  5. MagnumManiac

    MagnumManiac Well-Known Member

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    I DO NOT take primer appearance as an indication of excessive pressure. I have had loads that showed flattening on the start loads, this has almost always involved Fed215 primers, if I switch to WLRM primers with the same load, no flattening is evident.
    Ejector/extractor marks are number one for me, hard bolt lift is number two and loose primer pockets only show up when the other two occur.

    Cheers.
    gun)
     
  6. Beluebow

    Beluebow Well-Known Member

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  7. deadidarren

    deadidarren Well-Known Member

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    the one on the left is mild and the one on the right is way over it's flat and if you look at the P you will see the extractor mark on the case head.
    and these are cci 400 primers and are harder than most .
     

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  8. MagnumManiac

    MagnumManiac Well-Known Member

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    I'm sorry, but those pics and the accompanying text mean absolutely nothing, no mention is made of the actual pressure that made those primers look like that, what brand they were, all that is obvious is that a general assumption has been made.
    I have the Pressure TraceII system and I have seen primers such as the one on the end in that pic appear well below max pressure, as I stated, primer appearance means nothing unless you can compare it to a known standard, the same reason we now know that CUP testing was hit and miss and not accurate at all.
    First time loaders SHOULD take primer appearance as a guide to stop increasing the load when flat primers appear within the listed book loads, but it is NOT in any way telling you what pressures your loads are running at. They could be at max pressure, but they could also be well below max pressure.
     
  9. crittrgittr

    crittrgittr Well-Known Member

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    Thanx guys. I think I'm ok with my loads. According to Bluebow link I am in normal range. I don't have any ejector dents or damage to cases. just wanted to make sure after I heard a lot of talk about primers that mine were looking ok. Thanx again
     
  10. MontanaRifleman

    MontanaRifleman Well-Known Member

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    IMO, if you don't have pressure equipment, which I don't, the best way to gauge your pressure is by the brass. If your primer pockets are holding up OK, then your pressures should be OK. For factory Rem, Win and Fed brass, I usually look for about firings or more. That can vary from brand to brand and cartridge to cartridge.

    I think brass is the best pressure indicator other than actual pressure measuring equipment.
     
  11. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    forgot the # count Montana....:D

    If you aren't getting three to 5 firings from most brass you are stepping on the gas too hard. I usually go with a bigger caliber, let her loap a bit, and the brass will neck crack before the pockets fail. Pounding on little cartridges to make them perform just beats everything up too much. If you are significantly over factory/ book specs for a combination, it is likely your pressures are higher too.
     
  12. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    The other thing I saw there was no mention of the headspace allowed for the fired casings. More headspace = flatter primers.
     
  13. MontanaRifleman

    MontanaRifleman Well-Known Member

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  14. MontanaRifleman

    MontanaRifleman Well-Known Member

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    Yup, some different factors affecting primers and it's not all pressure. Good to look at primers but it's a little like looking at tea leaves.