Sako A III small screw on underside of cocking piece

Discussion in 'Miscellaneous Sako parts' started by sempreelk, Aug 16, 2021.

  1. sempreelk

    sempreelk Active Member

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    There is a small screw on the underside of the cocking piece on my A III rifle. What purpose does this screw serve?


    Thanks
    IMG_2504.JPG
    Ed
     

  2. gunner620

    gunner620 Well-Known Member

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    sempreelk, that screw locks the firing pin so it will not move and cause the firing pin protrusion to increase. It should be checked occasionally to make sure it is tight. Be careful not to damage the screw slot (some may have a metric allen) use a proper fitting screw driver or allen wrench as not to damage it. Some later cocking pieces do not allow the owner to tinker with adjusting the firing pin protrusion. Jim
     
  3. sempreelk

    sempreelk Active Member

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    Jim,

    Thanks for the info. I just recently bought this pin and that's how it showed up. My current firing pin does not have this feature and the hole does not even appear to be threaded.

    Ed
     
  4. gunner620

    gunner620 Well-Known Member

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    Yes, that's the kind that keeps you from messing with the adjustment of the firing pin. You would not believe what screws some people turn not knowing what can result. Jim
     
  5. sempreelk

    sempreelk Active Member

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    Jim
    Once again many thanks.

    Ed
     
  6. gunner620

    gunner620 Well-Known Member

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    One more thing , since that firing pin assembly appears to have been monkeyed with, if you install it be sure to get the pin protrusion checked it should be .059 to .071 Jim
     
  7. sempreelk

    sempreelk Active Member

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    I was just thinking about that, going to check it on both firing pins.
    Thanks
    Ed
     
  8. sempreelk

    sempreelk Active Member

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    Jim,
    Checked both firing pins for protrusion. They were exactly the same .062 .

    Once again , Thanks for the info

    Ed
     
  9. tilleyman

    tilleyman Well-Known Member

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    If you ever lose one or the end is all galled up Mc Master Carr sells a set screw that is close to the Sako original profile.
    https://www.mcmaster.com/92905A603/
    M3x0.5 x 10mm extended tip set screw used in the A and L series cocking piece to retain the firing pin... some pins were drilled so the set screw can only go in one pre-set place.

    A little tricky to install which is why the firing pin has a slot in the end so you can minutely revolve it... when concentric the stepped end of the set screw drops snugly into the hole.

    Others had a lateral groove milled in the firing pin which allowed a much greater degree of adjustment (1.0 mm per full revolution) till the groove lines up with the screw again to reach 1.5 to 1.8mm firing pin protrusion.

    If the hole or groove is missed and the set screw tightened it can gall up the threads on the firing pin... a M6 x1.0 HSS die nut will clean them back up.
     
    Last edited: Aug 18, 2021
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  10. sempreelk

    sempreelk Active Member

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    Thank you very much for that. I saw a screw on another site for 34.95 and I just SMH.
     
  11. kevinlg

    kevinlg Well-Known Member

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    I once had a custom Sako that actually had the firing pin cross-threaded into the cocking piece. So, long ago, I invested in a set of M6x 1.0 taps and die. They've come in very handy, as they also work with the two action screw locations.

    As for the set screw......on the full thread firing pin....if I have to rotate the pin to a position other than the factory "drilled" dimple, I put a lead shot below the set screw and carefully tighten the screw. Never had one move.
    After tightening the set screw I fill its recess with clear fingernail polish(on both styles of the adjustable Sako firing pin). It won't let the screw back out, and can be easily removed with a dental pick if needed.

    Also......tilleyman.....I'm pretty sure you meant to type "(1.0mm per full revolution)". Ok? :)
     
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  12. tilleyman

    tilleyman Well-Known Member

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    Pretty sure I meant to type what I did... but was thinking of the M3 x 0.5mm... corrected ;)
    But yes a M6 x 1.0 firing pin advances 1.0mm per full revolution and the M3 x 0.5mm set screw advances 0.5mm!
     
    Last edited: Aug 18, 2021
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