When a rifle scope can’t be accurately sighted, it is common for owners to make the assumption that the scope is broken. The most likely issue is that the scope has run out of adjustment, and now it will no longer sight in. It is important to understand that when this happens, the scope, itself, is not broken, at least this is true approximately 99 percent of the time. It simply means that the scope has run out of adjustment. The actual problem is discovering what caused the scope to utilize so much adjust in the first place.
Faulty Mounting Hardware
One of the most common causes of the need for excessive adjustment of a rifle scope is the mounting hardware, the base and rings. Quality is immensely important when it comes to scopes and the hardware used to mount them on rifles. If the base or rings are of poor quality, or if they are improperly installed, they will have the capacity to cause the scope to be grossly misaligned with the bore, meaning that the scope will not have enough internal capacity to compensate for the misalignment. Read here for our recommended list of quality rifle scopes.
Testing the Mounting Hardware
When there are sighting problems with a rifle scope, the first step is to check the mounting hardware to make sure that is properly installed and that the parts are of good quality. While it may be easy to understand why poor installation can create a sighting problem, it may be difficult to understand how poor quality effects sighting. Imagine just one bolt that should be level, but the poor casting process has left it with a slight slant. That slant can significantly impact the alignment of the scope with the bore.
There are a number of techniques that can be used to determine if the mounting hardware is the culprit in the sighting issues associated with the scope. When using weaver rings and experiencing exhausted adjustment capacity to the left or right, make note of where the target is at the point that the adjustment ran out. Then, remount the rings 180 degrees from where they were initially mounted. Once you complete this process, try sighting the scope again, if you run out of adjustment to the opposite side of the original adjustment issue, then it is the rings. A common practice for providing an immediate remedy is to turn one of the rings around, and this will often allow the scoped to be sighted in. However, it is recommended to replace the rings with quality rings.
For the person who is using Redfield rings, and you run out of adjustment to the left or right, the problem, in this case, is more than likely that the rings are not properly centered. First check to make sure that it is not a centering issue. If the rings are centered, then follow the same steps as with the Weaver rings.
Another Common Cause
While the most common culprit to sighting issues with a rifle scope is mounting hardware, there is a secondary culprit — mounting holes in the rifle that are drilled off center. The challenge here is that detecting whether the holes are off center can be extremely difficult without the proper measuring tools. If the holes are severely off, it will be easier to detect.
There are occasions in which the scope is the actual problem. This happens when the internal workings of the scope are not properly responding to the external adjustment mechanism on the scope. The internal adjustment mechanisms can either get stuck or they will tend to jump all of the place. The easiest way to determine if it is the internal adjustment mechanisms is to center the reticle and then observe the movement of the crosshairs.
When there are problems with the internal adjustment mechanism, then the scope will either have to be repaired or replaced, but in most instances, it is something outside of the scope that is causing the problem.
You can find more on rifle scope repair here.