Problem with Vintage Sako Scope Mounts

Discussion in 'General Sako Discussions' started by South Pender, Jul 5, 2019.

  1. South Pender

    South Pender Well-Known Member

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    I'd been looking for a set of vintage Sako scope mounts (the original ones with the 50-50 rings), and located a set that appeared to be good condition with the bluing completely intact. When I took them apart, however, I saw that one of the top ring screws was not quite right. While the other 7 (four on each ring) were the correct and original M3.5x.6x6mm screws, the one screw was slightly different (having a countersunk head, rather then the flat-bottom head of the correct screws) and had been threaded into the ring hole. I'm guessing that someone used an Imperial screw (like a 6x48) as a substitute for the correct metric screw. It appears that some damage has been done to the threads of the mount hole, as when I tried to thread in a proper M3.5x.6x6mm screw into the hole, I encountered resistance, suggesting that it was not threading properly.

    Using a little force, I can get the proper screw to go all the way down, but I'm not confident that it is holding properly. So I'd be grateful for any advice about how to proceed. These are four-screw rings, so perhaps having one of the screws not quite right won't present a big problem, but I'm not convinced of this. Another thought I had was to loctite (blue) that one screw and hope that this will make up for the buggered threads.


    I'm not keen on the more extensive fix of reaming out the hole, re-threading and going with a completely different screw, as I'm not confident that a new screw would fit properly into the top of the ring without a lot of fussy reworking.

    What are your thoughts on this? What would you do under the circumstances? (Short of looking for a new set of mounts!)
     
    Last edited: Jul 6, 2019

  2. marlin92

    marlin92 Well-Known Member

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    Bummer - what do the threads on the screw look like on the proper screw after forcing it down and removing it? If they seem to not be damaged - maybe work it in and out slowly dripping oil as you do it, much like when using a tap and see if it gets easier and solves the issue. Only other option I can think of is if you can obtain the proper tap and chase the threads.
    Good Luck
     
  3. Chris Anderson

    Chris Anderson Well-Known Member

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    What caliber is the rifle?

    If it's a big boomer and there'd be a lot of force on the rings/screws then it might be something I'd worry about. If it's a 222 or equivalent I'd just make sure the other screws are tightened to spec and tighten the damaged screw as much as I dared.

    If the scope slipping is your concern I've heard of shooters using black electrical tape between the scope and the rings but there are LOTS of suggestions in this thread:

    Scope Slip & Loctite on Mounts

    All that said I've never done anything special when mounting my scopes and I've never had a problem. I've only got one big boomer (a 300 Win) but I don't shoot that very often as the smaller calibers are so much more fun to shoot.

    Good luck. Let us know what you decide and how it turns out.

    Chris

     
  4. icebear

    icebear Well-Known Member

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    Marlin's advice is good. Clean out the threads on the ring thoroughly before doing anything else. Usually substituting a 6-48 or similar screw does not cause significant damage to the threads in the bottom ring, as the rings are typically made of harder metal than the screws. Metal shavings left over from the incorrect screw could be the cause for the resistance in putting in a correct screw. I'd advise cleaning the threads thoroughly and shining a small light into the hole to check the condition of the threads. They are most likely OK, with little or no real damage. I've seen many Sako rings with incorrect screws and none of them had stripped threads.

    There is even a screw pack on the market that is advertised "for Ruger and Sako." It is impossible for one set of screws to fit properly in both Ruger and Sako rings, since they are different threads. The Ruger screws will go into the Sako rings, but they won't hold properly. I recently took a set of these out of Sako rings and the screws were chewed up but the rings were fine once I cleaned the crud out of the threads.
     
    Last edited: Jul 16, 2019
  5. South Pender

    South Pender Well-Known Member

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    Thanks for the insights, guys. Chris, it's a 270 Win. I read through the Sniper's Hide thread and found it informative. They mention using rosin on the rings, and that's something I've always done when mounting scopes, even with my rimfires where it's undoubtedly unnecessary. Marlin92 and icebear, I'll give the screw hole a good inspection and try cleaning it up.
     
    Last edited: Jul 6, 2019

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