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Thread: perforated primers

  1. #1

    perforated primers

    What are the causes for perforated primers? Firing pins design or what? I have two single shot rifles that do this, one a RB the other is a Stevens 94 that I've stubbed to 7x30 Waters. Both using reduced loads. The RB is 7mm Mauser cal.

  2. #2
    Boolit Master tazman's Avatar
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    Where is the primer getting the hole?
    If in the center, it is usually a too sharp firing pin.
    Occasionally you can get a batch of primers that have thin cups. These will puncture no matter the pressure. I had that problem with a batch of Remington primers a few years ago.
    I would try a different batch of primers to make sure it is the gun rather than the components..

  3. #3
    Boolit Buddy redhawk0's Avatar
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    I agree...I'd try a different primer first...CCIs are pretty tough...you might start with one of those...Rem is soft and Win falls in between.

    The firing pin could also be just a tad too long.

    redhawk

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  4. #4
    Boolit Master
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    Taz is right, we need to know where on the primer the perforation occurs. If it is along the edge, it could be due to incorrect treatment during manufacture. Winchester replaced a case of 5000 for me not to long ago for this reason.

  5. #5
    Boolit Master


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    I have a CZ American 22 hornet that punctured the primers about every other one and it turned out to be the firing pin length was to long. I shortened it and reprofiled it and have not had another problem. Great rifle by the way!

    Ken

  6. #6
    Boolit Grand Master

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    Profile of the firing pin ( a small ring or rough surface), size smaller pins create a smaller tighter indent that is more apt to pierce, to long may literally push thru the cup, a oversized hole around the firing pin allows for cratering and or the cup to be blown out. If no small disks have been seen or found its more likely to long a pin or to sharp. Maybe chipped with a small sharp edge. If small disks have been seen ( the actual dent from the primer blown out) you may have a bushing problem in the breech block to firing pin fit.

  7. #7
    Boolit Master tazman's Avatar
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    Quote Originally Posted by Tatume View Post
    Taz is right, we need to know where on the primer the perforation occurs. If it is along the edge, it could be due to incorrect treatment during manufacture. Winchester replaced a case of 5000 for me not to long ago for this reason.
    Was that the discolored primers that we talked about a while back?

  8. #8
    The blown primers look like the metal is extruded into the firing pin hole. When I push the firing pin in it protrudes just a hair over a 1/16" past the breech block. No disks found so I suspect the pins are too long. If I shorten the pins should I keep the same profile or more blunt?

  9. #9

    perforated primers

    I forgot to say they are CCIs.

  10. #10
    Boolit Master tazman's Avatar
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    A picture of the point would help to make a determination on what the shape should be if you can get one.

  11. #11
    Boolit Buddy
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    pic of the blown primers would be helpful too.

  12. #12
    Boolit Master
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    Quote Originally Posted by Tatume View Post
    Taz is right, we need to know where on the primer the perforation occurs. If it is along the edge, it could be due to incorrect treatment during manufacture. Winchester replaced a case of 5000 for me not to long ago for this reason.
    Quote Originally Posted by tazman View Post
    Was that the discolored primers that we talked about a while back?
    No. It turns out that primer cups are cleaned in an acid bath to remove lubricant used in the drawing process and to clean any tarnish, before the primer is assembled. The acid is neutralized after cleaning. These were insufficiently treated, and the residual acid weakened the brass cups.

  13. #13
    Boolit Buddy
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    If the firing pin hole is too large for the firing pin diameter you can get perforated primers. Sometimes a weak hammer or striker spring will let the pin move back under pressure.

  14. #14
    Boolit Master tazman's Avatar
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    Quote Originally Posted by Tatume View Post
    No. It turns out that primer cups are cleaned in an acid bath to remove lubricant used in the drawing process and to clean any tarnish, before the primer is assembled. The acid is neutralized after cleaning. These were insufficiently treated, and the residual acid weakened the brass cups.
    Makes sense. I am glad they admitted what was wrong with them.

  15. #15
    Boolit Buddy
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    What should I think? 2 different lots of 20g slugs.
    Newest lot this year pierced. Older last year lot no pierce. Both same brand.

    Two other brands no pierce.


    Some hits are dead center, others are a bit off center on all brands. Pierced ones are both centered and off center.

    Using a CVA 20g slug gun new last year. Can't be more than 30 rounds total fired.
    Most of the tanks are gone and the windows don't rattle anymore. I won't be able to sleep now.

  16. #16
    Boolit Master knifemaker's Avatar
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    If that firing pin sticks out more then 55 thousand from the breech face, your problem just may be a too long firing pin and you will need to shorten it to around 50-55 thousand and test it. Keep as close to the factory nose profile as you can. You may have to go shorter if the problem is still there at 50-55 thousand from breech face.

  17. #17
    With the hammer pushed all the way forward the pins protrude almost 3/32" even a 1/16" is .0625 which is too long. I'll be fixing this soon as I'd like to use these this Deer season.

  18. #18
    Boolit Master



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    regarding the 7mm RB, I have found some that had home-made firing pins out of drill rod and which were to long. You might have a homemade one in yours
    atr
    Death to every foe and traitor and hurrah, my boys, for freedom !

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check