Rifle scope power refers to the amount of magnification provided by a particular scope. Choosing the best rifle scope power is a matter of determining what type of shooting you plan to do with the combination of weapon and scope. You must take into account the type of target and the distance at which you will be shooting. You may also want to take into account the caliber of the weapon, although this is not as important.
The main consideration in choosing the best rifle scope power is distance to the potential target. This is extremely important, as using a scope with a very high magnification on a target at a range of under 100 yards (90 meters) can result in very narrow field of view. It can be difficult or impossible, under these conditions, to find the target or distinguish a shot location on large game such as whitetail deer.
The type of terrain where you will be shooting will also affect your decision. In many wooded areas where whitetail deer are hunted, most shots are taken at ranges of 100 yards (90 meters) or less. In these conditions, a magnification range of 3x to 9x is more than sufficient. In more open areas, where game may be hunted at a range of up to several hundred yards, a scope with an upper magnification limit of up to 12x or 14x may be desirable. For extreme long range shooting, or for hunting small game at longer ranges, you may want a scope with an upper magnification limit of as much as 25x.
Many rifle scopes are adjustable, and this gives the hunter greater flexibility in sighting targets. Targets at closer ranges are well suited to lower magnifications and targets at higher ranges can be effectively sighted with the upper magnifications. Some shooters, however, prefer simple fixed power scopes, such as a 4x rifle scope, an all-purpose scope that is good for most shooting and hunting under a variety of conditions.
Target shooters often prefer a higher rifle scope power for a given range than a hunter. This is because the targets are small and the field of view does not need to be as large as that needed by a hunter. Hunters need to be able to see the entire animal in their field of view to execute an effective shot, while a target shooter needs a very narrow field of view in order to make a very precise shot on a small target.