scope shim question...

[rich337]

Hey guys, I'm going p doggin next week, and I just realized that my .22 mag is shooting an inch low at 100 yards even with the scope dialed all the way up. Unfortunately, I don't have time to do anything more than shimming the rear ring with black electric tape for now. My question is: how much elevation will I obtain with 1 layer of tape between scope and ring? Should I use a couple layers?

thanks all,

 

[bohemR13]

Measure the center to center distance of the 2 rings and tell me how thick each layer of tape is.

To get c2c distance just measure the outside and subtract 1 ring width.

It's a similar triangle problem. Calculate the tape thickness,total) divided by the distance between ring center. Measure in inches.

[,tape thickness) /,c2c distance) ] * 3600 inches. = vertical change at 100y in inches. If you want to convert to MOA divide by 1.047

Example. Assume tape is 0.010' thick total, rings are 5' apart. That means you get

[0.01/5]*3600 = 7.2 inches of vertical change at 100y --> 6.877 MOA.

PM me if you have questions, I don't check here very often.

 

[Cheechako]

1 MOA is 1.047' at 100 yards. 100 yards is 3600'. So, 1.047/3600.000 = .00029'.

So, figure .00029' per MOA per inch of ring spacing.

Ray

 

[bohemR13]

Dammit, and here I've been doing it the hard way.

 

[Cheechako]

No, you haven't been doing it the hard way. You've been doing it a different way.

I'm sure there is an i-pod out there that will do it at the push of a button.

Ray

 

[Fred Bohl]

You might find on of these helpful:

Scope Mounting Tilt Calculator

Sight Correction Calculator

 

[rich337]

Thanks guys I knew you'd come through for me! Don't feel bad cheechako, I like the logic behind your calculations as they take into account the distance between rings. I hope my tape job works out for this year.

 

[Ackman]

It's not so uncommon for a barrel to not be perfectly straight with the receiver. You don't say what rings or mounts are on the gun. But before you start screwing around with shims tape or raising lowering one end of a scope, understand what's going on.

Each ring is a rigid tube that clamps to the scope. Both rings have to be on the same centerline. Mess with raising one of them and those centerlines are now out of alignmentt, then what happens? The scope is put under stress and has to bend or dent to fit the rings. It's a good way to mess up a scope. The solution is Burris Signature rings. Or use a one piece base and raise one end.

 

[rich337]

Thanks for the heads up. I am aware that the rings are now putting stress on the scope,a low end Bushnell) . It's not what I prefer, but my time has all but run out, and I cannot shim under the base since it is a ruger 77/22 magnum. Even if I could do it a better way, it will have to wait until next year's p-dog trip. I am waaaaaaaaaaaaaay too anxious to try the new Hornady 30 grainers on dogs to not bring the gun even if it's rigged up bad. At this point, I'm too excited to care.

:crazy: