Cranky Farmer

Shimming a scope .... how to????

7 posts in this topic

I am here in Missouri and actually getting to SHOOT my AR's! I've got a 223 and my 25 WSSM uppers that I am shooting and trying to get zero'ed in. The 25 shot GREAT and I am getting ready to start shooting it at 100 yards and get it where I want it.Anyway, the scope on my 223 upper is shooting WAY high at 25 yards. Even after i crank the elevation down as far as it will go I am 3 inches high at 25 yards. How do I go about shimming this scope to get closer to zero and allow me a little room for adjustments?The 223 is shooting tight groups and the scope and my mount are both tight.Thanks!!

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Heath, get an aluminum beer or soda can and a pair of scissors to cut some small shims from. Just cut some small strips of can wide enough to fit the width of the scope rings. Remove the front ring top and slip a few of the shims you made under the scope to raise the scope slightly. You will have to loosen both rings to get the shims under. Just tighten the scope rings down with the shims in place and you should have plenty of adjustment. Try and make your shims to fit the lower ring as closely as possible and don't over tighten the rings when replacing them.

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One thing that you need to remember is that on AR rifles the scope is typically three inches higher than the bore so they are difficult to zero at ranges less than 100 yards. Shoot it at 100 yards and I'll bet it is alot closer to zero.

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Hum. :( My AR's are flat top receivers as are Heath's and mine isn't that high up. Maybe with a scope on the handle of an AR. But both of mine had plenty of scope adjustment when I first shot them. Even at 50 yards it isn't far off. It all depends on the scope and I think he's going to need some shims. :lol::lol:

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Yes, both of mine are flat tops like John says. This 223 upper is driving me NUTS! We got some shims made last night but ran out of light to shoot it. I am packing up to start my drive back to CA so I may not have time to shoot it. I will leave it for my brother to goof with, though.

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Mine's a flat top also but I have the high mount on it because the stock is so straight. Try Burris Z type rings they have the offset inserts up to .020".DSC00356.jpg

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The Burris rings are the way to go. I had them on my HBAR with medium rings. I put a +10 MOA on the rear and a -10 MOA on the front for a total of 20 MOA in elevation. Both front and rear had '0' rings for the tops. My scope was mounted 4.5" above boreline. With this setup and a Leupold 3-9x50 scope, I could aim dead on out to 300+ yards with a 100 yard zero and still hit a 4" target. My Leupold's elevation was almost bottomed out.

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