Ruger Mk IV plug screw tool question

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  • SkiPatrolDude

    Ultimate Member
    MDS Supporter
    Oct 24, 2017
    3,377
    Timonium-Lutherville
    Hi all,

    Wondering If anyone has any insight into what tool is used for the Ruger Mk series plug screws.

    I have a Mk IV Target in Stainless Steel and I removed the front sight post and want to use the plug screws it came with to fill the void.

    I managed to jimmy them out with a small steel punch when I put on a red dot, but can’t get the plugs back in since it requires more torque than I can apply with a simple punch.

    Looks to be a very fine star hex wrench pattern. Any idea what size?

    I know they make flat head screws but wanted to see if I can get these originals back in.
    Thanks
     

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    fred55

    Senior
    Aug 24, 2016
    1,775
    Spotsylvania Co. VA
    Just checked my Mark IV and the sight is a 5/64 hex. If you have a star pattern those are Torx heads, T10 or perhaps T8. fred55
     
    Last edited:

    SkiPatrolDude

    Ultimate Member
    MDS Supporter
    Oct 24, 2017
    3,377
    Timonium-Lutherville
    Just checked my Mark IV and the sight is a 5/64 hex. If you have a star pattern those are Torx heads, T10 or perhaps T8. fred55

    Ah, there is a bit of confusion I think.

    The site post is indeed 5/64 hex bit. What I am referring to is the small plug screws that are in the tapped weaver mount holes near the rear sight. The plug screws are the same thread dimensions as the site post screw, but require different tools.

    It almost looks like a very fine Torx pattern but is very hard to tell. It's definitely smaller than a 5/64 bit.
     

    fred55

    Senior
    Aug 24, 2016
    1,775
    Spotsylvania Co. VA
    Ok, those three screws are referred to as Barrel Receiver Filler Screws. My eyes are not able to determine what head is on those screws. It’s hard to imagine being able to get the torque required to remove or install those screws. Try calling Ruger or a local gunsmith and see what they say? Sorry, fred55
     

    SkiPatrolDude

    Ultimate Member
    MDS Supporter
    Oct 24, 2017
    3,377
    Timonium-Lutherville
    Ok, those three screws are referred to as Barrel Receiver Filler Screws. My eyes are not able to determine what head is on those screws. It’s hard to imagine being able to get the torque required to remove or install those screws. Try calling Ruger or a local gunsmith and see what they say? Sorry, fred55

    Thank you for the advice, much appreciated.
     

    Magnumite

    Ultimate Member
    Dec 17, 2007
    6,571
    Harford County, Maryland
    No first hand experience with that screw but just knowing what is typically used, try the following hex wrench sizes. That may get you what you need.

    In standard: .050”, 1/16”, and a .090” (3/32”)
    In metric: 1.5mm, 2mm and. 2.5mm
     

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