Help Needed to Modify Screwdriver for Scope Rings

South Pender

South Pender

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This is probably an odd request, but I need to have a notch cut in a screwdriver bit used to tighten some vintage Sako scope mounts. A shooter on the Sako forum made one, and it is pictured below. I don't have the tools to do this myself, and I can't imagine a machine shop in Vancouver being willing to do it. You can see in the first picture that it is needed to tighten a nut that has the bolt protrude into the slot in the nut. In the second picture, I've laid out the dimensions.

So I'm wondering whether one of the gunsmiths on this forum could do it for me. I could provide all measurements along with the bit (from the Brownells set). Of course, I'm prepared to pay for this work. I'm guessing that it could probably be done in 30 min. or less by someone with the right tools.

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I think I have a set of those rings. Could modify a screwdriver to fit, and mail it to you. But the postage alone for a small parcel would be at least $15.
Surely there must be someone in Vancouver with a Dremel.
 
You can buy a set of security bits from many different hardware stores for reasonable money - they have multiple bits to choose from.
 
Look close at that nut in your picture. The edges of the slot are "thrown up" - aka "buggered" - that comes from using a screw driver that is tapered and too narrow. The driver needs to be as thick as that screw slot and parallel walled (or slightly hollow ground) so the turning torque is applied evenly across the bottom of the screw slot. As shown, the top edges have seen the force, and have deformed. If you are making one, may as well make it fit correctly.
 
That 'nut' is quite screwed up... just wrap a piece of thin leather around it and use pliers. Once you have it set for the correct windage you don't need to adjust it again... and you only adjust it when the big nut on the other side is loose...

But honestly, if you can't buy a screw driver and a file, and file a notch in the screw driver... maybe you shouldn't be mounting your own scope either... take it to a smith...
 
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Potashminer said:
Look close at that nut in your picture. The edges of the slot are "thrown up" - aka "buggered" - that comes from using a screw driver that is tapered and too narrow. The driver needs to be as thick as that screw slot and parallel walled (or slightly hollow ground) so the turning torque is applied evenly across the bottom of the screw slot. As shown, the top edges have seen the force, and have deformed. If you are making one, may as well make it fit correctly.
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Yes, that's not my mount; it's a picture of someone else's. My mounts are new and pristine, and I'd like a bit that fits the slot as closely as possible. The bit that I have and is in the second picture is a Brownells 340-4 bit, which is a parallel-ground blade (not tapered) and it fits the slot perfectly (except for the notch that is needed); the tip is .035" thick (which matches the slot almost perfectly and .34"wide, where the nut is .36" in diameter. So I'd like to use this bit.

guntech said:
That 'nut' is quite screwed up... just wrap a piece of thin leather around it and use pliers. Once you have it set for the correct windage you don't need to adjust it again... and you only adjust it when the big nut on the other side is loose...

But honestly, if you can't buy a screw driver and a file, and file a notch in the screw driver... maybe you shouldn't be mounting your own scope either... take it to a smith...
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Yes, I know the drill with vintage Sako mounts; I've used them before. I can use hand-tightness with that windage screw and do the final tightening with the large thumb screw on the opposite side. I have a close-fitting screwdriver bit for that larger thumb screw (it's the Weaver clamp screw bit from Brownells) to give it just a little more tightness than hand-tightness. So the screwdriver bit that I'm talking about is not absolutely necessary, but it would be nice to have. There was a discussion about this recently on the Sako Collectors Club forum where getting a screwdriver for this windage-adjustment nut was discussed, and I thought it would be a nice addition to my toolkit. I guess I could go out and try to find the right triangular or Swiss file and do the work myself, but these Brownells Magna-tip bits are super hard, and I don't have a Dremel tool or any power tools to speed up the work--nor do I have the time for this right now. Just for the record, guntech, I've mounted dozens of scopes over the years....
 
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I actually have a set with this bit. Bought at princess auto years ago. If I bought it , it must have been ridiculously cheap.
 
You just need a spanner bit set.
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I have this tamperproof multi bit that probably has the right size. It’s come in handy many times

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As has been said, a vise and a small file or two will get you squared away. A hobby magnifier would probably help. File, and fit, file and fit. If you take it easy you should be able to make it very easily.
 
South Pender said:
Yes, that's not my mount; it's a picture of someone else's. My mounts are new and pristine, and I'd like a bit that fits the slot as closely as possible. The bit that I have and is in the second picture is a Brownells 340-4 bit, which is a parallel-ground blade (not tapered) and it fits the slot perfectly (except for the notch that is needed); the tip is .035" thick (which matches the slot almost perfectly and .34"wide, where the nut is .36" in diameter. So I'd like to use this bit.


Yes, I know the drill with vintage Sako mounts; I've used them before. I can use hand-tightness with that windage screw and do the final tightening with the large thumb screw on the opposite side. I have a close-fitting screwdriver bit for that larger thumb screw (it's the Weaver clamp screw bit from Brownells) to give it just a little more tightness than hand-tightness. So the screwdriver bit that I'm talking about is not absolutely necessary, but it would be nice to have. Just for the record, guntech, I've mounted dozens of scopes over the years....
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This is good to hear... your original post implied a considerable lack of know how...
 
Just go to the bolt store and get a proper hex nut to fit. Why waste your time on silly fasteners, you’d be far better off to get a nut made if you can’t match the thread than to get a tool made. Then you can torque it properly.
 
Uisge said:
Just go to the bolt store and get a proper hex nut to fit. Why waste your time on silly fasteners, you’d be far better off to get a nut made if you can’t match the thread than to get a tool made. Then you can torque it properly.
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You do not torque that 'nut' and a hex nut would look ridiculous and unless machined to fit where it is supposed to fit, it would not work at all.
 
guntech said:
You do not torque that 'nut' and a hex nut would look ridiculous and unless machined to fit where it is supposed to fit, it would not work at all.
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There are many different styles on fasteners to choose from. One that requires a custom screwdriver is the one that looks ridiculous to me, especially after it’s mangled like the one in the picture. However, I have that particular screwdriver, it came in a Mac tools screwdriver set along with all the other ridiculous tamperproof bits. But I get it, form over function. I R HD mechanic, making special tools to take things apart is nothing new to me, gets on my nerves a bit though lol.
 
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