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shimming my scope base

Discussion in 'Rifle Country' started by wade rigsby, Nov 25, 2009.

  1. wade rigsby

    wade rigsby Well-Known Member

    may sound stupid to most but it is a question that has been on my mind for a few days.

    right now my zero is taking up half the elevation on my scope. if I shim the front scope base would it allow me to utilize more of my scopes elevation. I am not talking much just a little. if I didn't have the elevation to get out to 1000 yds then would raising the front not give me more elevation capability.
  2. dmazur

    dmazur Well-Known Member

    Shim the rear base for longer range. This tilts the line of the muzzle up with respect to the scope's LOS.
  3. Maverick223

    Maverick223 Well-Known Member

    +1, seems counterintuitive, but think of it this way: you want to shoot up, so you need to look down further.

    I have never done it (but do use tapered bases), but have heard that feeler gauges work well.

  4. wade rigsby

    wade rigsby Well-Known Member

    sounds like it makes sence. I'll try it.
  5. Tang419

    Tang419 Well-Known Member

    I'm putting a 20 MOA base on my .300 RUM Sendero.
  6. PT1911

    PT1911 Well-Known Member

    I personally hate the idea of shimming but that is just me.... if you must, go with the advice given.
  7. dmazur

    dmazur Well-Known Member

    I don't recommend shimming, either. It's a quick solution, but there's always the worry of the shim working loose, "wracking" the scope tube, etc.

    As long as the shim is relatively thin, and the solution involves something like Acra-Glas, I've heard of good results.

    I had a horrible scope base alignment problem involving Ruger integral mount quarter-ribs. Due to the angled design of the mount, shimming the rings wouldn't work. Also, there was a large windage error as well as elevation error.

    I finally solved the windage component with windage adjustable rings made to fit Ruger mounts, and then I lapped the front ring to remove the excess height. (Rifle was shooting so low scope adjustments couldn't compensate...)

    This takes an incredible amount of time and involves a lot of valve lapping compound and at least a year's worth of patience. After getting the front ring low enough, I had to reduce the thickness of the "ears" to restore clamping, and then lap both rings to restore a parallel mount. Ugh!
  8. Offfhand

    Offfhand Well-Known Member

    If you shim only one base the rings will no longer be in alignment, thus causing a kinked, bent or even dented scope when rings are tightened. Maverick has the right suggestion: get tapered bases.
  9. dmazur

    dmazur Well-Known Member

    It can be hard to get a tapered base that corrects the amount you need. If you can get them to fit your rifle, the Burris mounts/rings that accept the adjustable inserts are the way to go, IMO.

    These come in 0, 5, 10, 15 MOA, I believe.

    (But they don't make them for Ruger integral mounts...)
  10. Uncle Mike

    Uncle Mike Well-Known Member

    Shimming .... BAD!

    You'll trash your scope....
    Get proper the proper base that offers built in angle.
  11. Maverick223

    Maverick223 Well-Known Member

    If you decide to go with a tapered base (and one is available for your rifle), I would recommend going with one that offers as much elevation as your scope can correct for (without having to adjust to the far extreme to zero). I went with a generous 40MOA base on my long range rifle (but my optics provides 107MOA to correct for this at 100yds).

  12. Offfhand

    Offfhand Well-Known Member

    Hey Gentlemen, after thinking it over: In case this question comes up again, a scope can be neatly shimmed for additional elevation if using a ONE PIECE base. This way the rings remain in good alignment, no problem. This way, economically, one base works for both long and short range shooting, at the price of only one base. For long range only I would still agree that a dedicated taper base is the way to go. But I may give some thought to manufacturing tapered and matched shims: rear higher than front shim of course, and both tapered so angles coincide on a straight plain. Any market potential? Or is someone already making these? Thanks for your thoughts.
    Last edited: Nov 26, 2009
  13. Uncle Mike

    Uncle Mike Well-Known Member

    I find it hard to believe no tapered bases exist for your rifle!
  14. Maverick223

    Maverick223 Well-Known Member

    I doubt it, but if properly constructed it would be a good improvement...but, you would have to make a set for each rifle (and long and short action variants), as the distance between the mounts are not constant.

    Which brings about a good question...what is it (rifle and optics)?

  15. wade rigsby

    wade rigsby Well-Known Member

    remington 700 BDL/338 remington ultra mag. scope leupold. according to the ballistics tables and my scope. I cannot get enough elevation out of my scope to get me to 1000 yds. I have a two piece base. but with the advise you guys have given looks like I will be buying a one piece.
  16. Maverick223

    Maverick223 Well-Known Member

    There are Nightforce, IOR, and Badger just off the top of my head (and there are plenty more that I forgot).

  17. Sir Aardvark

    Sir Aardvark Well-Known Member

  18. docsleepy

    docsleepy Well-Known Member

    do a little math to figure out how much shimming you need. In my case, it was on the order of .010 inch. I had a piece of plastic about that, cut it with scizzors, punched a hole, and bingo, able to get the scope to work. In my case, this probably IMPROVED the fit for the scope. Anyway, with metal dowels in both rings, they match perfectly. It has worked perfectly ever since. I bought some thin brass to make replacement shim, but never did it yet. The plastic did just fine.

    Probably worth getting some aligment dowels and checking if you don't have a one piece base, as pointed out by a previous post.
  19. wade rigsby

    wade rigsby Well-Known Member

    thanks guys I never knew these type of scope bases existed
  20. Maverick223

    Maverick223 Well-Known Member

    NP, glad to be of service.


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