Firing pin hole size?

Discussion in 'Gunsmithing' started by bigngreen, Feb 29, 2012.

  1. bigngreen

    bigngreen Well-Known Member

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    I was checking out a new bolt on PT&G new web site and the last thing to choose is what firing pin hole size, .075 or .062. Having not ran into this I was wondering if there would be an advantage to going to a small hole and firing pin and if so what would it be?
     
  2. rscott5028

    rscott5028 Well-Known Member

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    My swag would be smaller equals lower mass therefore faster lock time and less influence on the rifle prior to ignition.

    But, waiting to hear the correct answer from the pros.

    thanks!
    richard
     

  3. Edd

    Edd Well-Known Member

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    I'd use the .062 for small primers and the .075 for large ones.
     
  4. Coyboy

    Coyboy Well-Known Member

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    Thats about the jist of it. The difference is only in the pins tip(last .300-.400")

    The small primers help keep case head expansion minimized, thus guys will run those cartridges hotter (examples 6br, 6.5x47 lapua) The large fire pin tips will pierce the small primers or show cratering faster than a small FP tip. This has more to do with cup displacement, the small tip displaces less, thus it thins less.

    so if your planning on a hot 6.5x47L get a small pin.
    If your doing a 260 rem, the large is fine.
     
  5. rscott5028

    rscott5028 Well-Known Member

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    Sometimes it almost seems too simple.

    -- richard
     
  6. bigngreen

    bigngreen Well-Known Member

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    I was researching it and noticed that there are a couple custom receivers that use the small firing pin hole and pin when used in high pressure situations with large rounds like the 338 Lapua improved which doesn't fit the application I'm looking at but I do have a 6.5x47 Lapua on the list so good info, Thanks!!
     
  7. ultraedge

    ultraedge Well-Known Member

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    On a 700 Rem action reducing the size of the firing pin hole and using a .062 diameter firing pin will normally stop primers from piercing if that was an issue.Look up firing pin hole bushing at GRETAN. I have had one done and it works just like he said.No more problems in that department. Gary Campbell