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Thread: Scope being drive back with recoil

  1. #1
    Member ekberger's Avatar
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    Default Scope being drive back with recoil

    I recently put Schmidt and Bender 1.5-6 X 42 scope on my Sako .375 H&H. The scope is mounted with Sako's quick release rings. Scope is 30mm in diameter and rings are sized accordingly. Alignment is good and set-up shoots well.

    The problem I had both times since shooting this set-up is that the scope keeps getting driven backwards in the rings after repeated firings. Naturally, the first question is are the rings tight and I'd have to answer yes. There are 4, 2.5 mm socket head screws on each ring. From what I can tell I'm tightening them down evenly using a properly sized allen wrench to the point that I'm afraid to tighten them any further, i.e., damaging a screw, bending the wrench or damaging the scope barrel itself. When this happened the first time I simply thought that I had not tightened them enough initially so before going out the second time I loosened everything up and slid the scope forward in the rings and really cranked them down. However, much to my disappointment after about 15 rounds the scope was once again moving backwards in the rings. I don't have much room to play with, perhaps 2-3mm of the scope's barrel length in the quick release mounts before the variable adjustment ring wedges itself into the scopes mount, therefore it needs to stay in place.

    I have never experienced this with any other scopes I've mounted so I'm wondering if anyone has any ideas for me to try.

    Regards,

    Eric

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    Rings aren't tight enough.
    Great spirits have always found violent opposition from mediocre minds. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence. Albert Einstein

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  3. #3

    Default Try Talley Rings?

    I had the same experience with my .375 H&H, using Warne Maxima rings. The good guys at Boondock Sporting Goods in Eagle River convinced me to try a set of the Talley integrated rings/bases and "problem solved". I know Talley makes Sako style rings and bases.

    One of my friends is a gunsmith--he suggested using powdered rosin? I guess it is something like what you put on a violin bow, but I am not sure it is the same. He said it would fix the problem, but I put the Talley rings on before I tried it, so I don't know if it would have actually worked.

    Good Luck!
    Jim

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    Member 1Cor15:19's Avatar
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    Default

    I regularly coat the inside of my rings with rubber cement, a very thin coat, and have never had an issue with slippage afterwards.

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    Default Backwards or forwards?

    Eric-

    When the rifle is fired the gun recoils back while the inertia of the scope tends to make it remain in place. In effect the scope then tends to creep forward in the rings relative to the rifle. With a heavier scope like yours the mass is greater so the slippage is more likely.

    I started a thread on scope slippage a month or so ago. There was a lot of good suggestions in the thread from a lot of nice experienced shooters. Check it out and you will learn a great deal.

    Quote Originally Posted by ekberger View Post
    I recently put Schmidt and Bender 1.5-6 X 42 scope on my Sako .375 H&H. The scope is mounted with Sako's quick release rings. Scope is 30mm in diameter and rings are sized accordingly. Alignment is good and set-up shoots well.

    ......

    I have never experienced this with any other scopes I've mounted so I'm wondering if anyone has any ideas for me to try.

    Regards,

    Eric
    Living the urban lifestyle so I can pay my way and for my family's needs, and support my country. And you?
    ".. ask not what your country can do for you, ask what you can do for your country" JFK

  6. #6
    Member ekberger's Avatar
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    Default It's Forward

    Yes, you're correct the slippage of the scope is forward; I had to think about that for a moment.

    I searched the forum suggested and yes, there are some good ideas for me to try. Incidentally, I've seen references to lapping the rings previously, however, the Sako Optilock ring mounts have an internal spherical fastening ring (Sako indicates that these are patented) so I'm not sure that would be a feasible thing to do on the fastening rings themselves as they are loose until secured down by the outer rings.

    I did note that there was a light film of oil on the inside of the rings and on the bearing surfaces of the internal spherical fastening rings when I installed the scope. I thought that this was intended for corrosion control so I left it. Perhaps one of the first steps is to degrease the bearing surfaces of these parts. I did notice that each time the scope moved there was a light film of oil on the scope tube.

    Thanks for all the helpful suggestions, I have some things to try.

    Regards,

    Eric

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    Member marshall's Avatar
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    Default

    Quote Originally Posted by ekberger View Post
    I did note that there was a light film of oil on the inside of the rings and on the bearing surfaces of the internal spherical fastening rings when I installed the scope. I thought that this was intended for corrosion control so I left it.
    Eric
    Eric,

    A film of oil is bad. It will create a barrier much like an engine has a film of oil between the main bearings and the crank. That film will prevent metal to metal contact and you will have slippage.

    Use a good cleaner, something like break cleaner on a soft clean rag to remove oil and other particles between your rings and scope. You will have a much better contact surface.

    Don't let that cleaner come in contact with your lens. It will harm your high dollar coatings.

    MM

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    Member sayak's Avatar
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    Default True: clean off all traces of oil...

    ... then use the ultra thin, double-stick tape (looks like Scotch tape but is tacky on both sides) to cure the problem. It worked for me and was a very cheap cure. But I'll bet the rubber cement idea would work well too.

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    Member 1Cor15:19's Avatar
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    Quote Originally Posted by marshall View Post
    Use a good cleaner, something like break cleaner on a soft clean rag to remove oil and other particles between your rings and scope. You will have a much better contact surface.

    Don't let that cleaner come in contact with your lens. It will harm your high dollar coatings.

    MM
    I agree with marshall; make certain the rings are absolutely clean. I assumed that fact when I suggested to use rubber cement, I should have mentioned it myself. As for types of cleaner, it's hard to beat rubbing alcohol as a cheap solvent and it's lens friendly as well.

  10. #10

    Default

    I always degrease rings and scopes before mounting and have never a had a problem. I agree with removing all the oil.

  11. #11
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    Default Alcohol

    Buy the 100% or 99% rubbing alcohol instead of the common 70% stuff - it is a bit harder to find but worth the trouble to locate.

    As far as I can determine alcohol is lens friendly - I see it listed as an ingredent in a lot of lens cleaners. I use it to wash off really dirty lenses on scopes that have a coating of oil and dirty. With a soft lenes brush and a lot of alcohol most stuff with come off without any risk of scratching the coatings.

    For the rings I'd use brake cleaner - it dissolves about everything and does not leave a film. For the scope alcohol is the best bet as advised.

    Quote Originally Posted by 1Cor15:19 View Post
    I agree with marshall; make certain the rings are absolutely clean. I assumed that fact when I suggested to use rubber cement, I should have mentioned it myself. As for types of cleaner, it's hard to beat rubbing alcohol as a cheap solvent and it's lens friendly as well.
    Living the urban lifestyle so I can pay my way and for my family's needs, and support my country. And you?
    ".. ask not what your country can do for you, ask what you can do for your country" JFK

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    MEK and liquid electrical tape

  13. #13

    Default

    I had the same problem with my NF scope mounted in NF rings mounted on a 300 RUM. Interestingly enough, there were no scratches on the tube from the slippage. No oil or grease was present and I use a Wheeler FAT torque wrench to torque my action screws, base screws and ring screws. And I usually torque them about 5 inch lbs more than recommended for the high recoil of the RUM. I called NF about it nad they said they hadn't heard of such a problem before.

    Both the NF and S&B are fairly heavy scopes and in these cases mounted on high recoil cartridges. Some shooters with high recoil rilfes and heavy scopes will use double sets of rings. I've read users of Burris Signature rings with plastic inserts don't have the same problem and I'm considering switching over

    There are 4, 2.5 mm socket head screws on each ring. From what I can tell I'm tightening them down evenly using a properly sized allen wrench to the point that I'm afraid to tighten them any further, i.e., damaging a screw, bending the wrench or damaging the scope barrel itself. When this happened the first time I simply thought that I had not tightened them enough initially so before going out the second time I loosened everything up and slid the scope forward in the rings and really cranked them down.
    You really should get a torque wrench and I'm surprised no one has mentioned it yet - especially the "professionals". Trying to "feel" your way with an allen wrench is NOT the way you want to do it. Too littel torque is not good and too much torque could result in damage to your screws, bases, and/or rings, not to mention lack of consistancy.

  14. #14
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    Default Wheeler Engineering...at MidwayUSA

    Although new at this, I did try lapping scope rings using this cool kit by Wheeler Engineering: http://www.midwayusa.com/viewproduct...tnumber=187492. The instructions made it very easy. I did a little at a time, checking progress often. Seeing the high spots wear down with the 220 grit lapping compound on the ring halves was interesting.

    I actually ordered a different Wheeler kit, which included an adjustable torque screwdriver for tightening the torq screws. Pretty cool package that worked as advertised. The gun wasn't a magnum rifle, but the concept was to provide to maximum grip surface for secure scope mounting and to reduce the chance of machine marks on the rings marring the scope.

    Chuck Hawks reviewed one of the fancier Wheeler kits here: http://www.chuckhawks.com/wheeler_sc...unting_kit.htm

    Good luck.

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    Default The question I have is...

    that no one asked, your scope professionally mounted? There's some alignment issued you could be having with installing it yourself...or unlapped rings...

  16. #16
    Member ekberger's Avatar
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    Default Scope was not "professionally mounted"

    To answer your question the scope was mounted by myself. These rings have a plastic inner sleeve that slips over the scope tube that sits inside of the outer mounts. I understand the concept of lapping and alignment, so your point is well taken. Alignment of the outer rings is relatively straightforward, however, I did not think that one could lap the plastic inserts to accomplish what one does to a standard metal ring. An attempt to do so would simply result in the plastic slipping around and may cause more harm than good.

    My thanks all who have taken the time to contribute to this post, especially for all of their suggestions and professional help and advice. I have thoroughly cleaned the oil off of the rings and components and have remounted the scope. In the process I used the recommended tightening sequence for the top ring mounts and have torqued each screw according to manufactures specifications. Which by the way are listed as 15-17 inch pounds. I am in the process of loading some rounds to see if I have made any progress. I will report my results.

    Eric
    Last edited by ekberger; 06-15-2010 at 02:49. Reason: Spelling

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    Member ekberger's Avatar
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    Default Update on the scope movement issue

    First off I'd like to express my gratitude to everyone who has provided input on my problem. I have found the suggestions helpful and hopefully others will as well.

    It's kind of hard to describe what I have learned without taking photos of the rings, but I'm reluctant to take things apart at this point so that I can photograph this, therefore I will do my best. Here is a link to Sako's website which describes the Optilock Quickmount, or quick detachable scope mounts. Unfortunately the image does not show the slit in the inner ring that I have found to be important with regard to orientation.

    http://www.sako.fi/optilockproducts.php?quickmount

    I degreased everything according to suggestions. I decided to try the least messy solution and that was to apply rosin to the internal ring parts. Rosin is frequently used in the machinist trade to prevent slipping of parts. To make a long story short, I tightened everyting down and torqued the ring screws to specifications, i.e., 15-17 in lbs. Satisfied that I had solved the problem I headed to the range. Much to my disappointment I had the same issue, the scope was being driven forward with recoil in spite of my best efforts to get in aligned and tight. So I stopped my load testing and went back to the workbench.

    After studying the situation, I noted that the orientation of the slit in the inner ring might not be clamping tightly due to the way I had it oriented. Intuitively, I thought that it might be good to have the slit in the inner polycarbonate ring oriented downwards so that water would drain out; 180 degrees opposite this would have the slit oriented upwards. The slit in the inner ring allows one to slip it over the scope tube before installing the outer clamping rings.

    However, when I got to thinking about optimal clamping pressure from the outer metal ring on to the inner plastic ring it was obvious that it might be better to have the slit sitting horizontally, or in-line with the opening of the outer ring so that when the top halves of the rings were tightened down, the inner ring would have maximum amount of pressure exerted upon it by the outer ring. So I did this...

    Again, thinking that I might be on to something, I headed to the range. Much to my surprise, I got little to no movement of the scope. I'd say it's not 100%, real or imagined, but I think I might be on to something. Just in case someone asks, there were no mounting instructions with these rings. I can't say for certain that I've completely solved the problem. This is a heavy scope and the rifle produces a lot of recoil but after 20+ rounds today, I'm feeling that I may be on top of the issue.

    Lessons learned...by all means degrease everything, use a proper torquing sequence and optimal tightness and if you're faced with these internal rings pay attention to the orientation of the slot. This in no means should indicate that other ideas might have been equally important, I just didn't try them all.

    What might apply however is this..."The person interested in success has to learn to view failure as a healthy, inevitable part of the process of getting to the top" - Dr. Joyce Brothers.

    Regards,

    Eric
    Last edited by ekberger; 06-26-2010 at 16:11. Reason: Spelling

  18. #18
    Member gunbugs's Avatar
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    Default

    To measure any apparent movement, just use a pencil and mark a line on the scope body just at the forward edge of the front or rear ring. If after a few shots your pencil line moves away from the ring, then you know you still have movement. If it stays put, all is well.
    "A strong body makes the mind strong. As to the species of exercises, I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise, and independence to the mind."

  19. #19
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    Thumbs up Sako Rings and Warne Rings

    I use Warne rings on most of my rifles never had a problem with them.

    The older Sako rings worked great also.

  20. #20
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    Quote Originally Posted by ekberger View Post
    Much to my surprise, I got little to no movement of the scope. I'd say it's not 100%, real or imagined, but I think I might be on to something.

    Regards,

    Eric
    I've not tried marking a scope with a pencil as gunbugs suggested, but it ought to work. When I want to be certain a scope is staying put I place one drop of clear nail polish on the underneath side where the scope and ring meet. If the seal is broken the scope has shifted.

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