Bushed Firing Pin Hole on 7mmRemMag

Discussion in 'Advanced Gunsmithing & Engineering' started by fe1, Jan 29, 2013.

  1. fe1

    fe1 Site $$ Contributor

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    Is there any need for busing the firing pin hole on a
    Rem700 7mmRemMag?
    I knew it was common on small primers but not large primers.
     
  2. Preacher

    Preacher Site $$ Contributor

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    If your not blanking primers, there is no need to bush the pin..
     
  3. fe1

    fe1 Site $$ Contributor

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    Preacher, Thanks for the reply.The term "Blanking Primers",does that mean the firing pin is not contacting the primer?
     
  4. Preacher

    Preacher Site $$ Contributor

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    Nope, it means the primer is pushing material out and around the firing pin hole, and it raises a small circle
    that you can see on the flat of the primer...
    A nice snug fit of the pin and the hole prevents that...
     
  5. pdhntr

    pdhntr Site $$ Contributor

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    Interesting. It was my understanding that "blanking" was when the firing pin actually pierced the primer and produced a small little hole at the bottom of the indentation. The term comes from blank pistols that often pierce the primers in exactly the same way when they are fired.

    And this is why refs that use (cheap) starter pistols are often wearing protection on their arm.

    What you describe above, I was taught is called "cratering".

    Jim
     
  6. Eddie Harren

    Eddie Harren Site $$ Contributor

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    Jim, that has always been my understanding as well. I always called what Preacher described as "cratering".
     
  7. Preacher

    Preacher Site $$ Contributor

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    This is what a blanked primer looks like.....
    Some folks also call it cratering, 6 of one, and a half dozen of the other...
    It still needs to be tended to....

    [​IMG]
     
  8. Eddie Harren

    Eddie Harren Site $$ Contributor

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  9. LHSmith

    LHSmith Site $$ Contributor

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    My intro to "blanking" was at the '05 IBS Score natl's, ~ 95' F @noon and using Russian non-mag primers in a 6 PPC, on last shot to finish target...no go bang...tried again ...trigger won't drop FP.........run to trailer where Sid Goodling was reloading....."Yup, you must have "blanked" a primer, and got crap in the trigger"....Somethings stay etched in your brain forever.
    The only other issues since have been FTF's with a lot of Fed. 205's, as I never went back to the Russian non-mag's again for the ppc or BR.
    FWIW Preachers pic is what I have come to know as cratering.
     
  10. Larryh128

    Larryh128 Site $$ Contributor

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    Either way, if it exists , it needs to be fixed. It's not that exspensive.
     
  11. Hal

    Hal

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    The picture that Preacher posted is what a cratered primer looks like.

    Blanking a primer is when a small disc is blown out of the face of the primmer.
    The disc ends up in your bolt body.

    Hal
     
  12. lloydx2

    lloydx2

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    Cratering is what precedes blanking (cookie cutting). The unsupported part of the primer flows back into the pin hole to the point where it cant stretch any further and tears loose. While its doing this it is moving the firing pin back too. Sometimes a weak firing pin spring can cause cratering, blanking too. But is usually caused by to much pressure. Theres a lot of advantages to bushing a pin. More efficient less disruptive ignition = smaller groups.
     
  13. fdshuster

    fdshuster Site $$ Contributor

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    Call it whatever you like, but I had small (firing pin diameter) holes blown in my CCIBR4 & 450 primers.

    Sent the bolt to Gre-Tan and had the firing pin bushed (Rem 700) = end of problem. Total cost was about $80 with a 7 day turn-around time.
     

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