The torque wrench isn't necessary, but is vital to those that have a habit of overdoing things.
* - If your gun has a Picatinny rail then this rail is your mount, otherwise mounts vary from flat rails, claw mounts, side mounts, and many other options.
** - Yes, a penny. You didn't know the Government gave us cheap scope adjustment tools on a daily basis did you? :smoker:
Step 0 - Zero the Scope
While not absolutely necessary, you will want to do this if you expect to do long distance shooting. Start with the adjustment knob all the way over on the stop and count the number of clicks to the opposite stop. Then adjust the scope to the midpoint. Do this for both the windage and elevation.
Step 1 - Mount your Base
If your gun has a picatinny rail already, skip this step.
You will want to mount your base in a firm manner. Be careful not to exceed torque ratings otherwise you will strip the threads on the gun. On most bolt action rifles the base is secured by 4 small screws. Most semi-auto guns like G3s, AKs, M1As, and FALs require side mounts or claw mounts that attach either via clamps or bolts.
For ultra long range shooting you may opt for a 20 MOA base. This is a raked base that allows you to vary the height of the scope as well as gain elevation adjustment range.
Step 2 - Mount your Rings
Mounting rings properly is vital to maintaining adjustment range, keeping your scope in place, and in some cases, keeping your scope in one piece.
The number one effective mistake people make is improperly mounting the lower section of the ring. Weaver style rings that are "windage adjustable" allow you to vary the alignment of the rings themselves. If you haphazardly install them you can take out a significant amount of your windage adjustment.
To avoid this you will want to set the rings on the base, hand tighten them, and lay the scope on just the bottom half of the ring. Visually look at the scope from above and correct any misalignment by adjusting the front and rear ring bases accordingly.
Tighten both bases to the rail, and lay the scope on top.
Step 3 - Setting Eye Relief
BEFORE YOU TIGHTEN ANYTHING, VERIFY THAT THE SCOPE IS NOT TOUCHING, OR IS GOING TO TOUCH ANYTHING ON THE RIFLE. FAILURE TO DO SO CAN DESTROY THE SCOPE.
Place the upper half of the rings on the scope and hand tighten the screws.
BE SURE TO TIGHTEN IN A CROSS PATTERN IN SMALL INCREMENTS.
If you go in a cross pattern in slow increments it will ensure there is no stress riser in the rail and that the rings are optimally seated to the scope body. It will also prevent you from stripping the screws and ring bases.
Set the scope to the highest magnification, if it is variable. Adjust the parallax to it's lowest setting, if applicable.
Mount the gun like you would typically and see how well the eye relief suits your posture. If you have to move your head to any point that does not feel comfortable, or not easily repeatable, then you need to adjust the scope further in or out. Loosen the caps and adjust. Tighten in the above pattern. Adjust as necessary.
One thing to note, you do not want the scope ring to ride the turret. Make sure you have sufficient space on the scope that the ring tops are not going to sit on the turret or bell.
BE SURE THE SCOPE IS NOT TOUCHING THE RIFLE.
Step 4 - Alignment
This is another crucial part of mounting your scope. Before you tighten the scope down you need to look through the scope and reference the crosshairs to the midline of the gun. If the crosshairs are tilted then your scope adjustment will track in a diagonal line when you try to zero the rifle.
Turn the scope until the crosshairs are properly inline. You now want to tighten the ring uppers in the same manner as you did before, in a cross pattern in small increments. If you don't do this properly you will end up turning the scope and the crosshairs will be tilted.
Re-check that the crosshairs are centered after tightening. Adjust as necessary.
Step 5 - Bore Sighting the Gun
Time to use that penny! Penny's work best for most scopes as they fit nicely in the channel cut into the windage and elevation adjustment knobs.
Set the magnification down to around 6 - 9x
We use a BSA bore sight kit at work that works pretty well. It uses a series of caliber rods that insert into the muzzle with a imaged scope attached. You simply look through the scope and you will see a square with a bunch of lines in it. You adjust the scope until the crosshairs are in the center of the square.
However, the emphasis of the bore sight is to maintain adjustment and correct any problems with the mounting job. If the crosshairs are off the square, or are significantly right or left I typically will loosen the front weaver ring base and bump it over just a hair to correct it. Finite adjustments are done with the elevation and windage knobs. This allows me to maintain the maximum adjustment range of the scope.
All movements using the scope should be done with you looking through the scope. You want to ensure that the scope is tracking properly as well as minimizing any issues related to parallax from re-mounting the gun.
You are now ready to go test fire and zero your scope. I think you'll find that spending a little time and effort mounting the scope will save you time, money, and fustration out on the range.