Shimming scope ring to raise POI

J

jhansman

New member
Hey all-
I've been reading threads from all over the interwebs saying that to raise the point of impact, you shim the rear of the base, NOT the ring. I've run out of elevation for my 4x32 scope on my AK, and now must use a six o'clock hold to get anywhere near the target's center at 50 yds. Granted, this is not a target weapon, but I need to know it will hit where I put the cross hairs when the zombies come shuffling toward me (I know; a head shot with a 12 gauge is SOP) ;) .

I've read that a piece cut out of a soda can serves this purpose nicely, but my brain says that the front of the scope needs raising, not the back. Can someone clarify this for me and possibly explain the optical physics involved so the "why" aspect of this issue makes sense? Many thanks.

BTW, the side mount on this rifle is up for replacement due to damage, so I'll probably have to go through sighting in again when I do replace it. I'm just looking for a temporary solution til then. TIA.
 
Last edited:
You can ring your scope tube (dent it) doing that because a shim on just one ring puts the rings on different planes, so their scope holes are no longer coaxial. Burris makes rings with their Pos-align feature that will compensate and allow you to shim one end. Otherwise, get a scope base that has the extra elevation already machined in. You can get them with a number of different amounts of elevation machined in, 20 moa, 30 moa, etc. They will keep conventional rings on the same plane to avoid damaging the scope.
 
Yes, the Burris solution seems to be the most recommended. I think I'll wait til I replace the mount, center and re-mount the scope, and see where she hits. If after that I'm still way off, I'll check out the Burris offering. Thanks.
 
I've run out of elevation for my 4x32 scope on my AK, and now must use a six o'clock hold to get anywhere near the target's center at 50 yds.
"but my brain says that the front of the scope needs raising, not the back. "
If you're unable to LOWER your POI adequately, you do need to raise the front of the scope. You DO NOT want a base machined for MORE elevation. I wouldn't mess with changing anything until you have the new mount.
 
Methods of adjustment aside, to answer your question. The goal is to raise the point of impact, to do this you lower your point of aim. With iron sights you adjust your rear sight in the direction you want your point of impact to go. Same with the scope.
 
The goal is to raise the point of impact, to do this you lower your point of aim.
Click to expand...

Using your example with iron sights, if I raise my rear sight, am I not changing the angle between it and the front sight? Interestingly, the only rifle I have with iron sights is the one I am having scope issues with. Perhaps this weekend I will remove the mount and experiment with the iron sights to see what the relative relationship is between front an rear.
 
Last edited:
When you adjust iron sights or a scope, you are adjusting the point of aim. If you are hitting 6" low, then you want to lower the point of aim by 6". You want the point of aim to be where the hole is. So you raise the rear sight or the rear of the scope. But Unclenick is right about the alignment issues. Unless you are going to hone the scope rings or you have a PEPR mount, you don't want to shim it.

The simple way to think about it is move the rear in the direction you want the shot to move. :-)
 
If you are hitting 6" low, then you want to lower the point of aim by 6".
Click to expand...
And in so doing, you are raising the POI? I am trying to picture this and not doing very well :o

Clearly, you guys understand the physics of all this better than I, so I will follow you lead. One other question (just to add to the confusion :p ): If my POI is low, then on the scope turret, I'm dialing in "Up," correct? If so, dare I ask what this is doing to the crosshairs of the reticle? Just trying to understand all this in a way that for me, it becomes knowledge and not magic.
 
Clearly, you guys understand the physics of all this better than I
Click to expand...
It's not really physics, it is two converging lines. One is your "line of sight", which runs through the scope to the target. The other is the "line of flight", which starts out in line with the rifle bore (then drops). Your job is to make those two lines cross at your "zero range". It might help if you don't think of it as changing the angle of the scope, think of it as changing where the lines cross.
 
Sorry, didn't see the second part. The scope is set up to make it easy, they've already done the hard work so yes, if you want to move the shot up, turn the dial in the up direction, if you want to move it left, turn the windage dial on the side in the Left direction. Nice and easy. :-) Let me think about what that does with the cross-hairs ..... might have to read up on that myself. ;-)
 
You must log in or register to reply here.
Back
Top