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Firing pin protrusion on CZ550

Discussion in 'Gunsmithing and Repairs' started by Blakenzy, Mar 20, 2013.

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  1. Blakenzy

    Blakenzy Member

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    How much firing pin protrusion is safe to have?

    I just bought a CZ 550 and when holding the bolt up in my hand, measuring with the rear end of a caliper I get roughly .065" from the bolt face. However when resting the bolt on its bolt sleeve/shroud against the table, the pin protrudes further and this number goes up by .02(~0.085).

    How does one go about adjusting the firing pin protrusion on a 550 (if at all necessary or possible)? I notice that there is a firing pin spring nut that can be shifted fore and aft, is that supposed to do anything?
     
  2. Jim K

    Jim K Member

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    I am not familiar with that gun, but .065" sounds about right, though some guns run a bit less or a bit more. Unless there are misfires from too little protrusion, there is no cause for concern.

    Contrary to a lot of nonsense, there is no way any properly shaped firing pin can penetrate a primer or cause "pierced" primers. Nor can any mainspring ever put in a gun drive a firing pin hard enough to pierce a primer. In fact, pierced primers are due to a too light firing pin blow, when the firing pin doesn't support the primer and lets it flow back into the firing pin hole.

    Jim
     
  3. Blakenzy

    Blakenzy Member

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    Oh, good to know.

    Just as a side note, moving that nut I mentioned back and forth has no noticeable effect on how much the firing pin sticks out.
     
  4. rcmodel

    rcmodel Member in memoriam

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    So, you got a new rifle and decided to fix it, even though it wasn't broke??

    Screw the firing pin nut back on all the way tight and leave it alone.

    rc
     
  5. Blakenzy

    Blakenzy Member

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    :D Yeah... I have been messing where I probably shouldn't have been a messing, but that is just me. Not really to try to 'fix it' but I have a craving curiosity to figure out what does what. If only firearm manuals were comprehensive and exhaustive...

    Any idea what that nut might do, other than hold the firing pin spring in place?
     
  6. Mizar

    Mizar Member

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    That nut serves just to hold the firing pin spring compressed. That's it. It's not for adjusting the FP's protrusion or for adjusting FP spring's tension. Don't mess with it - just shoot your new rifle and enjoy it.
    They are actually good enough - if some part is not mentioned or shown how to disassemble it usually indicates that the average owner is not supposed to mess with the said part and better leave it to the gunsmith. There is a reason why the small booklet you got is called "Owner's manual"... Workshop manuals or Repair manuals are something quite different, for the most people are boring to death and they are big and heavy books with lots of "useless" info ;)

    Boris
     
    Last edited: Mar 22, 2013
  7. rcmodel

    rcmodel Member in memoriam

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    Quite so in fact.

    The CZ 550 owners manual says right in it how to remove the striker assembly for cleaning.

    It further says further dissembly is not necessary, and not recommended.

    So again, don't screw with the firing pin nut.

    Oh wait!
    You already did!

    rc
     
  8. Blakenzy

    Blakenzy Member

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    OK RC, message received, I suck and you hate me.
     
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