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Thread: Scope ring lapping and bedding

  1. #1
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    Scope ring lapping and bedding

    Lapped and bedded the scope rings on my Sako project:

    Leupold rings installed:



    Closer view of the ridges that Leupold puts in their rings. They actually do a pretty good job:



    What I use for a compound. Ring bottoms have the compound applied:



    My home made lapping bar is a 1" bar, drilled/tapped 3/8X16 with a bolt as a handle:



    This is after a dozen strokes with fairly heavy pressure. I continued until the ridges were gone, then cleaned the rings with acetone:



    I used Pro Bed on these. Brownell's AcraGlas Gel really works well as it has Nylon in it....you want some flexibility. I used some medical grade Nylon powder and mixed that in with the Pro Bed:



    A light oil like this shotgun choke tube oil goes on the screws, ring tops and the outside of the rings. On the lapping bar, use the regular mold release agent that you normally use for bedding:



    Then lightly snug the caps down. The lapping bar handle goes to the side so it doesn't rotate:



    Curing:

    Last edited by Al Nyhus; 03-18-2020 at 07:45 AM.

  2. #2
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    Interesting method Al.... thank you!

  3. #3
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    Question Al N..........

    Have you tried including the upper ring caps during the lapping process?

    Results?......good?......bad?

    Just curious.

    Kevin

  4. #4
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    If the object is to get an accurate bedding job, Aren’t you supposed to use the actual scope that is going on the rifle, in the position that it will be finally mounted.

  5. #5
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    Quote Originally Posted by jackie schmidt View Post
    If the object is to get an accurate bedding job, Aren’t you supposed to use the actual scope that is going on the rifle, in the position that it will be finally mounted.
    Jackie, that's a darn good question.

    I started out bedding specific scopes to specific rings in the past but inevitably ended up changing scopes and/or rings around from gun to gun. Checking a half dozen 1" tube scopes here, they measure from .997 to 1.003. So....what do you bed to what?

    I look at ring bedding differently than action bedding. When bedding an action, we want a micron fit of a specific action to a specific stock. For rings, my goal is achieving as much contact surface as possible between the ring and scope tube while still allowing the bedding to conform (flex) a bit to fit a wide number of scopes. Done this way, pinched scope tubes become a thing of the past and the increased contact surface between the tube and the rings can help maintain p.o.i. consistency. And barring any serious receiver issues, the rings become pretty much 'universal' from gun to gun.

    Here's a good example of one I did not too long ago. It's a set of Talley rings on a short 700. The bases were first bedded to the receiver to equalize the ring heights. Laying the scope in the rings shows serious fit issues. Scope tube diameter was .998 on this scope. No knock on Talley...I use their rings a lot. But tolerances stack up and pretty soon this is what we end up with. Lapping and bedding addresses these issues.



    For myself, it's simply another area to bring under control and eliminate question marks. For others, they'll tighten the rings 'farmer tight' and happily go on their way. People win with both approaches.

    I'm sure I've posted these before...this is a set of Kelbly single screws that I did over 10 years ago. God knows how many rifles they've been on and how many scopes have sat in them.



    Another tool I use is the Base Align. Designed by the late Dan Hackett, it works with either Kelbly/Davidson style bases or Weaver/Picatinny bases and allows the bases to be aligned perfectly. I was using them on my Borden Alpine action in this pic.



    Good shootin'. -Al

  6. #6
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    Quote Originally Posted by Kevin Gullette View Post
    Have you tried including the upper ring caps during the lapping process? Results?......good?......bad? Just curious. Kevin
    I normally do the tops also, Kevin. The Kelbly's I posted have the tops done with AcraGlas Gel so the color is different than the bottoms.

    Good shootin'. -Al

  7. #7
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    I’m curious about bedding then lapping after, what the difference might be. It is a low torque system so 8k psi epoxy should be enough in the gaps.

  8. #8
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    Quote Originally Posted by Al Nyhus View Post
    Jackie, that's a darn good question.

    I started out bedding specific scopes to specific rings in the past but inevitably ended up changing scopes and/or rings around from gun to gun. Checking a half dozen 1" tube scopes here, they measure from .997 to 1.003. So....what do you bed to what?

    I look at ring bedding differently than action bedding. When bedding an action, we want a micron fit of a specific action to a specific stock. For rings, my goal is achieving as much contact surface as possible between the ring and scope tube while still allowing the bedding to conform (flex) a bit to fit a wide number of scopes. Done this way, pinched scope tubes become a thing of the past and the increased contact surface between the tube and the rings can help maintain p.o.i. consistency. And barring any serious receiver issues, the rings become pretty much 'universal' from gun to gun.

    Here's a good example of one I did not too long ago. It's a set of Talley rings on a short 700. The bases were first bedded to the receiver to equalize the ring heights. Laying the scope in the rings shows serious fit issues. Scope tube diameter was .998 on this scope. No knock on Talley...I use their rings a lot. But tolerances stack up and pretty soon this is what we end up with. Lapping and bedding addresses these issues.



    For myself, it's simply another area to bring under control and eliminate question marks. For others, they'll tighten the rings 'farmer tight' and happily go on their way. People win with both approaches.

    I'm sure I've posted these before...this is a set of Kelbly single screws that I did over 10 years ago. God knows how many rifles they've been on and how many scopes have sat in them.



    Another tool I use is the Base Align. Designed by the late Dan Hackett, it works with either Kelbly/Davidson style bases or Weaver/Picatinny bases and allows the bases to be aligned perfectly. I was using them on my Borden Alpine action in this pic.



    Good shootin'. -Al
    Al, Back when I was freezing 36 leupolds, Weavers, B&L’s, I did chuck some of the bare tubes up to see how true they were.

    None were really “straight”, all exhibited some runout when placed in a between centers setup, some, particularly Weavers, , were not even round by as much as 2 to 4 thousandths.

    Since the tube on the 36 Leupolds is so thin, it was not uncommon to get thoroughly used scopes with distorted tubes, probably from overclamping in out of round rings.

  9. #9
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    Would the Burris Z rings with the inserts eliminate the need for lapping? Just asking. Thanks.

  10. #10
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    Quote Originally Posted by jackie schmidt View Post
    Al, Back when I was freezing 36 leupolds, Weavers, B&L’s, I did chuck some of the bare tubes up to see how true they were.

    None were really “straight”, all exhibited some runout when placed in a between centers setup, some, particularly Weavers, , were not even round by as much as 2 to 4 thousandths.

    Since the tube on the 36 Leupolds is so thin, it was not uncommon to get thoroughly used scopes with distorted tubes, probably from overclamping in out of round rings.
    Yep. -Al

  11. #11
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    Quote Originally Posted by cootrp3 View Post
    Would the Burris Z rings with the inserts eliminate the need for lapping? Just asking. Thanks.
    They do, indeed.

    I've also used synthetic 30mm-to-1" scope ring reducers with very good results. On my 10.5 lb. 30BR, it had 30mm Kelbly double screw rings with a set of flanged 30mm-to-1" reducers and a 1" Sightron 36X scope. If you look closely at the pic, you can see the flange at the forward part of the ring. Worked great!

    Last edited by Al Nyhus; 03-19-2020 at 09:10 AM.

  12. #12
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    Al,

    You mentioned bedding the bases to the receiver to level things out. Wouldn't the lapping and bedding pretty much do the same thing, or am I missing something?

    Years ago, I read an article by Ross Seyfried wherein he described using the black, rubber liquid designed to coat tool handles via dipping on the scope rings of heavy recoiling rifles to prevent scope slippage. For those who swap scopes around frequently and are concerned about size variations from scope to scope, the somewhat pliable nature of the rubber coating would seem to negate any of these size differences.

    Good stuff, Al...keep em' coming.

    Justin

  13. #13
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    You can feel the difference when tightening bedded rings as apposed to "out of the box" rings. I hate scarred up scopes, lapping and bedding solves that. Plus, I have made 30MM to 1" inserts out of aluminum. Talk about a solid lock down tightening those!

  14. #14
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    Here's the result. If you compare this to the 'before' pic...even assuming that the 'ridges' were making 100% in contact...the 'after' pic clearly shows a doubling of the contact area. It's hard to see in these pics but a small file works to relieve the parting lines at the top. If you look back at the pic of the Kelbly rings, it's better of that area :





    On the ring tops, I lap them on the bar and repeat the process:


  15. #15
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    Quote Originally Posted by Zebra13 View Post
    Al,

    You mentioned bedding the bases to the receiver to level things out. Wouldn't the lapping and bedding pretty much do the same thing, or am I missing something? Justin
    Justin, bedding the bases to the receiver accomplishes several good things. Most importantly, it gives 100% contact between the base and the receiver. If you look at bases that have been mounted for any length of time, you'll see how little contact they really have. Secondly, equalizing the ring heights keeps from having to 'egg shape' the rings when lapping....we want to just enlarge a round hole, not distort it's shape. If the 'hole' we make is oval-shaped, whatever you use in the bedding process (scope tube, mandrel, lapping bar) will want to settle to the lowest point, effectively tipping the scope up or down when you're done. Finally, bedding the bases allows you to align the bases correctly front-to-rear. This keeps the windage adjustments of the scope more centered, at least to start with.

    All scopes work best when they're solidly mounted, stress free and with the windage & elevation adjustments as close to the center as possible.

    Just my approach to it. -Al

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