Why scope rings’ installation matters?

Evelyn: Stephen, are you free now? I've got a new problem.

Stephen: Yeah, just go ahead.

Evelyn: I found my scope can’t be zeroed even I used up almost all the adjustment.

Stephen: Let me have a look, hum, it looks like I find the problem. Do you still remember I once said the installation of scope rings would influence shooting a lot?

Evelyn: Of course! So the problem comes from scope rings’ installation?

Stephen:Yes, it’s one of the reasons and also the almost common one why you can’t zero your scope. Perhaps your scope rings are on a different axis, causing your scope to slant upward somewhat, or they are not in proper height for your shooting.

Evelyn: Can you elaborate on that?

Stephen: For example, If your scope rings are not properly installed on the rail, which may lead to the two rings to be misaligned, then scopes also not straight and level. Like picture 1 shows, the two rings one is slightly higher than the other or like picture 2 shows the axis of the bore of the rifle is not coincide with the axis of the scope.

Evelyn: I see. It's completely invisible to the naked eye!

Stephen: You may still use this scope in a short range shooting. Once you use it to shoot middle or long range target, even you use up all the adjustment, it can only barely get center aligned or not to the center(Picture 3). There will be a deviation, the longer the distance, the greater the deviation.

Evelyn: I had no idea that it could have such serious consequences.

Stephen: Not only that, but the adjustment may probably follow an Arc movement if you keep adjusting. There may be not enough adjustment range left for the other adjustment since you adjust the turrets too far or close to its extreme position.(See ‘Why can't your scope adjustment go straight?’ for details).

Generally speaking, you need to install your scope straight and level if you want to get the maximum adjustment on all direction.

Evelyn: I got it. How about the rings’ height?

Stephen: Oh, it’s quite important too. Being installed too low or too high both bring difficulties for shooting for instance can’t be center aligned.

In addition, the higher the scope mounted, the greater the angle between the aiming axis through the scope and the trajectory of the fired bullet. 

Evelyn:I didn't realize ring’s installation was so important!

Stephen: Yes. Sometimes we get some rings as freebies, but these rings are actually of very average quality. Some are even very poor quality. Like picture 4 shows, some rings’ center won't even coincide with each other if you mount them at different side. Moreover, you will find they are obviously not at their axial directions which is a problem caused during production.

Evelyn: What a bad news.

Stephen: We can only use them for fun, they can not afford long range or extreme long range. Furthermore, these rings are always not shockproof, sometimes they broken only after dozens of shots. We have to buy better rings for our scope. For long range or extreme long range shooting you had better use scope ring alignment lapping kit.

Evelyn: I got it! Thank you so much for today’s explanation!

Stephen: You are welcome!