Sako Scope Ring Tips (Use the proper tools)

Discussion in 'General Sako Discussions' started by icebear, Jan 20, 2019.

  1. icebear

    icebear Sako-addicted

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    Since we are getting quite a few new Sako shooters signing up, I thought it might be a good time for a post on how not to mess up the traditional style Sako scope rings. I have seen many, many of these rings messed up with burred screw heads and thumb nuts. This is almost always the result of using the wrong tools.


    First, the slotted screws holding the rings together. The key here is always to use a snugly fitting screwdriver with a parallel-ground blade. The drivers you get at the hardware store are almost always taper ground. A tapered blade will not fit snugly into the slot and sooner or later will slip, resulting in an ugly burr on the screw head. There are two kinds of gunsmith screwdrivers with parallel-ground blades - the one-piece type such as made by Grace, and a handle with interchangeable blades, the most popular of which is sold by Brownells. If you use the Brownells set, the correct blade for Sako ring screws is #210-3.

    For the large thumb nuts that hold the rings to the bases, the correct tool is a Weaver type driver. As with the screwdrivers, you can get either a one-piece tool or a tip for your magnetic handle. The small tool shown in the photo below was made by B-Square. I keep it in my range bag. The bit shown on a Brownells handle also came from Brownells. Most people try to tighten these with an ordinary screwdriver, which frequently results in a damaged slot when the driver slips.

    It is critically important for both the ring screws and the mounting nuts to press the driver into the slot all the way, and dead square to the screw. If the driver is at an off angle, it will slip.

    Reproduction ring screws are available from a custom shop in Montana for 30 bucks for a set of eight. At that price, it pays to be careful with the originals. Good luck finding spare thumb nuts - once in a while you'll find some in a batch of parts, but not often. The ring screws are M3.5 cheese head. Do NOT use the screws labeled by some sellers as "For Ruger or Sako." They will fit - sort of - but they are a US thread and do not fit properly. I have seen several sets of Sako rings that people have used these screws. The fit is sloppy and the screw threads are shiny from metal coming off as the screw rethreads itself. Fortunately, the screws are made of softer metal than Sako rings, so they don't typically damage the rings.

    From top: B-Square Weaver scope ring tool; Brownells handle with Brownells Weaver scope nut bit; Brownells handle with 210-3 bit; Grace screwdriver that fits Sako ring screws. Note the stepped tip on the Grace driver.
    Scope Ring Tools 1.JPG

    This photo shows the two types of parallel-ground screwdriver tips. The top one is a hollow grind that is flat and parallel at the tip. The lower blade, from a Grace screwdriver, has a stepped tip.
    Scope Ring Tools 2.JPG

    To put everything in one convenient post, I've added below another tool that I made for the windage nut on the other side of the Sako ring. I made it out of a gunsmith's shorty screwdriver, probably a cheap clone of a Grace driver. I did the work with a Dremel tool and a couple of Swiss files. It works fine. You need to be sure that the blade fits the slot and the center opening is wide enough to clear the stud on the ring. See pictures below; I've posted a slightly more complete explanation at the bottom of this thread.
    Scope Ring Tools 3.JPG Scope Ring Tools 4.JPG
     
    Last edited: Sep 4, 2020

  2. mlesh

    mlesh Active Member

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    Icebear,
    I need a set of screws, do you know the name of the gun shop in Montana. thanks mike
     
  3. icebear

    icebear Sako-addicted

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    mlesh:
    I think it is The Custom Shop or something like that. I thought I had it bookmarked but I just checked and I do not. You can also look on Gunbroker and eBay as they sell through both at the same price.
     
  4. kirkbridgershooters

    kirkbridgershooters Well-Known Member

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    It is Custom Shop Inc, located in Hamilton, Montana. Mike at Mike's Custom shop in Hamilton, Montana may also have them...
     
  5. icebear

    icebear Sako-addicted

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    Here's one more Sako scope ring tool, in addition to the ones I've already posted. To borrow a phrase from the Vegematic - This is not available in any stores - because I made it myself, and if you want one, you'll have to make it too.

    This is the tool for the windage adjustment nut on an old-style Sako ring. Normally you don't need a tool for this nut. It's knurled for finger operation, and you set this nut and then tighten the large nut on the other side. However, sometimes the nut gets gummed up, or frozen with rust, or the threads on the ring are buggered, or whatever and you need a tool to free it up. I made this tool out of a gunsmith's screwdriver. It works perfectly. The donor tool was either a Grace screwdriver or, more likely, a cheap clone of a Grace screwdriver. Note that it has a parallel ground blade, not the taper ground blade of a hardware store screwdriver. You could do the same thing to a Brownell's interchangeable tip. I did this with a Dremel tool and a couple of Swiss files. It was easy but time consuming to get it just right. You need to get the opening wide enough to get around the stud and deep enough to drive the nut all the way home if necessary. The pictures should show you what to do.
    Scope Ring Tools 3.JPG Scope Ring Tools 4.JPG
     
    71Scamp, Charles Witt and FLT like this.
  6. Texas Chinook

    Texas Chinook Member

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    Icebear,
    Nice! What's the width of the blade you used? I'm wondering if I can get a Weaver Clamp Screw Bit and grind it to fit this purpose... The width of a WCSB is 5/8"..
     
  7. icebear

    icebear Sako-addicted

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    The Weaver bit is NOT suitable to regrind for the much smaller nut on the other side. I'll have to get back to you on what Brownells bit would be most suitable. What you need is a straight blade that is the exact width of the nut and just the right blade thickness for the slot, then grind away the middle part with a Dremel and clean it up with a file. I have a complete set of Brownells bits that I can check, but they are in another building and I'll have to check later. The other alternative is a stepped-blade gunsmith's screwdriver like I used, but I just happened to have that lying around and it was the right size.
     
  8. Texas Chinook

    Texas Chinook Member

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    Sorry to persist... I'm glad you're going to research the best Brownells bit... but what is the width of the driver you modified? Thanks
     
  9. South Pender

    South Pender Well-Known Member

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    Icebear, does the Brownells Weaver scope nut bit fit the Sako mount thumb screw slot without slippage?

    Not to wander too far into the weeds on this topic, but I've been doing a little Googling and have found that the usual description of what we need here is either a "U-shape screwdriver bit" or a "spanner head screwdriver bit." There are thousands available online, but the problem is determining the right size for this application. One designation that I've seen is U4, U5, U6, U7, etc. Do you know what the actual sizes of these bits are? I'm guessing that the U-designation refers to the width of the cutout in the blade.

    Any insights would be greatly appreciated!
     
  10. icebear

    icebear Sako-addicted

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    Width is 0.34", which is almost exactly the OD of the knurled nut. Thickness is 0.0375".
     
  11. icebear

    icebear Sako-addicted

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    Actually, I think the Weaver driver is the perfect tool for the Sako thumb nut, and I think that the Sako nut was probably copied from Weaver. If you look closely at the Sako nut, you see that the screw slot is not straight, but dished. So, for best fit it requires a curved tool, with a cutout in the center for the stud. The Weaver tool is a very snug fit in the Sako slot, to the point where you sometimes have to jigger it around a bit to be sure you have it properly seated. Check out the photos below. Note how the tool stays in the slot and is almost fully seated, even though there is no pressure on it and the tool is kind of hanging in the slot. That's a snug fit. I have occasionally found it necessary to dress up the slot with a file to make the Weaver tool fit, especially if the slot has been buggered by the use of an improper tool (as is common).
    Scope Ring Tools 5.JPG Scope Ring Tools 6.JPG
     
    Last edited: Sep 5, 2020
  12. icebear

    icebear Sako-addicted

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    Further to the question of U-bits, spanner heads, etc. - I have no specific knowledge of this category of tools or how they are measured. I have occasionally used adjustable spanner wrenches for working on optical equipment, etc. but I've never had occasion to deal with U-bits or pre-made spanner drivers. I would guess that most of these, if they are screwdriver type tools, have straight blades rather than the curved blade needed for the Sako thumb nut. I've used adjustable width spanner wrenches with pins on the ends, but that's a completely different critter. I'd say just stick with the Weaver tool.
     
  13. icebear

    icebear Sako-addicted

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    For the benefit of all who may be interested, here are some dimensions for the Sako scope ring windage nut and tools to turn it.
    Diameter of nut: 0.36" (9mm)
    Diameter of stud: 0.16" (4mm)
    Minimum depth of center cutout for homemade tool: 0.08" (2mm)
    Best fitting Brownells bit to grind for a homemade tool: 340-5
    Diameter 0.34", thickness of bit 0.04"
     
  14. South Pender

    South Pender Well-Known Member

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    That's super-helpful, icebear. It looks as if the Brownells 340-5 bit is very close to the right thickness at .04". So in addition to grinding out the center gap, it would need a little thinning, but very little. My measurement of the 340-4 blade thickness is .035", so I wonder whether it would be close enough.
     
  15. icebear

    icebear Sako-addicted

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    I made my choice by test-fitting the bits into the slot of a ring I had on the bench. I did not test several different rings, so it is possible that some slots are a bit narrower and a 340-4 would be a better choice. It would still fit well enough that it wouldn't be likely to pop out, and it would eliminate the possibility that the thicker bit might not fit some nuts. There's so little difference between the two that I'd be comfortable with either.

    UPDATE: Upon further checking, it appears that the later version of the original Sako rings has a narrower slot and the 340-4 would be the best choice to ensure that the homemade tool fits all versions of the old-style Sako rings. See longer post below.
     
    Last edited: Sep 5, 2020
  16. Rogan Kinnear

    Rogan Kinnear Well-Known Member

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    Great post! Thank you
     
  17. icebear

    icebear Sako-addicted

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    I checked a few more rings to see if the slot width on the windage nuts was consistent. The 340-5 was a perfect snug fit on all of the old-style rings, but on the later version (old style mounting, but a wrap-around upper ring), the slot was narrower, requiring a 340-4. Accordingly, I would recommend that, for a bit that will fit all variations of the original-style Sako rings, the Brownells 340-4 bit is the best starting point.

    Here's a shot of the later style (new-old?) Sako rings.
    Late Medium Rings 2.JPG
     
  18. paulsonconstruction

    paulsonconstruction Sako-addicted

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    Every smith that works on guns, mounts, etc. makes or modifies tools for specific tasks. The Sako ringmounts are no exception. This thread is informative to those new to the Sako ringmount system & should be helpful to our members. Thanks to those who have contributed !!! This is a perfect example of what the forum should be about.
     
    Last edited: Sep 6, 2020
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  19. Texas Chinook

    Texas Chinook Member

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    I wish Brownells had a speedier delivery method.. at a more reasonable cost.. I don't mind paying for 2-day delivery when an item costs >$100 but it hurts when the item costs 4 bucks! Now I can't wait to get a 340-4...

    "Oh oh the Wells Fargo wagon is a coming down the street; I hope that it's coming to me..."
     
  20. Texas Chinook

    Texas Chinook Member

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    Hopefully a more helpful comment..

    I have a Forester/Bonanza #15 with tip width 0.311" and thickness 0.040 that will work if someone can't wait for a Brownells delivery..
     

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