Riflescopes come in two basic types – fixed-power and variable-power. Fixed-power scopes come with magnification preset and it cannot be changed. For hunters pursuing game year after year in similar conditions such as wooded areas or in heavy brush, shots may seldom be taken at game more than 100-yards away and powerful or adjustable magnification may not be necessary. Shooters who use traditionally shorter-range calibers and rimfires such as the .30-30, .45-70, .22LR or .17HMR also seldom have a need for more than a 4X scope. Advantages afforded by using a fixed-power scope include simplicity of operation and generally lower cost than variable-power counterparts.
Variable-power scopes offer greater versatility by providing a range of magnification that can be dialed down when hunting in forests and cover or dialed up when shooting at longer ranges in clearings and prairies. They can also help zero in on small targets that are far away and are favored both by varmint hunters and long-range competition shooters for this reason. Variable-power scopes do tend to cost a bit more than fixed-power scopes and can be more challenging to use when dialing turrets for elevation and windage on long shots.
Once you’ve determined which type of scope will best suit your needs and decided on a model, you want to select the proper bases and rings for mounting it on your rifle. The firearm manufacturer or a Cabela’s outfitter can assist you in selecting the proper bases and rings. You will need to be sure that your rifle is drilled and tapped to accept a scope mount first. If it is not, a gunsmith may be able to do the necessary work for you.
Bases should be mounted securely to the top of the receiver or barrel. Use of products such as Locktite® can help keep the bases snug, but you may want to mount the scope first without these to be sure you’re satisfied with your purchase as removal can be difficult once such products are applied. Be careful not to over-tighten the mounting screws as they can be stripped if you’re too aggressive. For that reason, the use of a torque screwdriver or torque wrench is recommended.
Once the bases are on the rifle, it’s time to mount the rings. The importance of proper ring alignment cannot be overstated. You also want to be sure that your rings will mount the scope as low as possible without the objective lens bell touching the barrel.
This will enhance accuracy and alignment of the scope with the bore. Don’t tighten one set of ring screws and move to another. Turn each screw a few turns and move on to the next, but leave enough room for you to be able to slide the scope fore and aft with slight resistance.
With the bases, rings and scope now on the rifle, shoulder the gun and look through the scope. Move the scope forward or backward in the rings until you have the desired amount of eye relief. You should be able to consistently mount the gun and see clearly through the scope immediately.
Next, turn the scope tube right or left so that the crosshairs are perfectly horizontal and vertical when you look through the sight. Focusing on a known vertical line such as the corner of a room where two walls meet can help, and certain boresighting tools can also assist with crosshair alignment. Once the eye relief and crosshair alignment are complete, finish tightening the ring screws to secure the scope. Your rifle is now ready for boresighting.
There are a number of boresighting tools available, and it is entirely up to you which kind you’d like to use. Whether you choose a laser boresighting system that is inserted into the rifle’s chamber or bore, or select a muzzle-mounted system, the important thing to remember is that boresighting is to "get you on paper" at 100 yards.
The rifle still needs to be sighted in at a range before you attempt to hunt.
At the shooting range, if the first few shots don’t hit a 24" x 24" paper target at 100 yards move the target closer to 25 yards. Adjust the scope windage and elevation turrets as necessary to get a good group at 25 yards, and then move the target back to 100 yards for final adjustments.
Mounting a scope yourself does require some time (usually 1-2 hours for first-timers), a clean, well-lit workstation and patience. But once your shots are hitting where you want them too, you’ll discover that it can be a rewarding experience and useful skill to have.