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Numbers on a Rifle Scope Explanation:

1st Number (left of the hyphen):

Let’s start with the power range first. Power range is also known as magnification levels, which gives us a fair idea of what it is. A magnification level is simply the level at which the object would be magnified compared to the naked eye. For example, 2x scope or “2 power” would mean it is magnified 2 times the size of the naked eye. Similarly 3x scope would be three times, 7x scope would be 7 times and so on.

Second Number (right of the hyphen):

The second number is the upper limit of the magnification level. For example 4-10×50. The two numbers show that it is a zoom lens or scope. The shooter can set any number between the two limits according to the need. Most scopes today have variable range. However, sometimes there is only one number. In that case, the scope stays fixed at the specific level of magnification and is unchangeable.

Third Number (the diameter):

The third number is the diameter of the objective lens; the end closest to the barrel. According to the principles of lenses and light, a bigger objective lens allows more light to pass through the lens, helping increase low light performance and clarity of the scope. So a 50 mm scope would have better brightness and clarity than a 20 mm lens.

Tube Diameter:

Next up is tube diameter. It is also a variable that needs to be considered when buying rifle scopes. The tube diameter is measured from the central part of the scope tube. The two common sizes are 1 inch and 30 mm diameters. The former is most commonly found, with the latter being found in some European products, is increasing with time too. Contrary to popular belief, the diameter doesn’t have anything to do with the allowance of light in the tube. It is helpful in giving more strength and rigidity to the rifle scope, due to the greater cross-sectional area. It also helps in having better windage and elevation adjustments.

Field of View (FOV):

Field of view (FOV) is another important aspect in scope buying. As the name implies, it is the extent of the observable world from the human eye or any optical device. In the case of rifle scopes, it is measured in feet or degrees at specific yardage. The power of the scope has an inverse relationship with FOV; as the magnification increases, the FOV decreases. One has to trade off one for the other. A bigger FOV is better for acquiring targets or following moving targets. An example of FOV is 100-150 ft @ 1000 yards and 1.5-3.1 degrees @ 1000 yards

Into Long-Range Shooting? Here’s a guide for you “What Scope Do I Need for 300 Yards?“

Mounting a scope on your AR-15 for the first time is a difficult task. It takes a lot of time and patience, and sometimes a few tries, to nail it perfectly. But don’t worry, we got your back covered.

Here’s How You Can Mount a Scope on AR 15

This guide will help you mount your rifle scope in the first attempt.

Items you need:

Torque wrench – used to attach the rifle scope mount to your AR-15
Scope mount – the link between the gun and scope; the part which attaches the scope to the gun
Hex bit screwdriver– used for tightening the screws on the scope
Bubble level – used to level all the parts for complete accuracy during installation
Rifle scope – the scope you have chosen to your AR-15
Gun or shooting rest – used to hold your AR-15 rifle in place for the installation.

Step 1 – Preparation:

You need to prepare your rifle and tools for the installation. Make sure that your rifle is empty, unloaded and the safety is on. Gun safety is vital not only during storage but also in processes such as accessory attachment/detachment, cleaning, etc. Fix it in the shooting rest so that it’s stable and tight for being worked on. Use the bubble level to check level. Checking the level on every step is key to successfully mounting your scope in the first attempt, as a mistake on any level could lead to wrong installation of the scope, ruining all your hard work.

Learn how far your scope needs to be from your eye!

Step 2 – Attaching the mount:

Attach your scope mount to the rifle. Place the mount on the top of the AR-15 and tighten its screws by hand so that it holds it place properly. Take the torque wrench and tighten the screws to secure it in place. Be careful about the torque limit on the screws as given by the scope mount instructions. Tightening it more could result in the mount being spoiled. Use the bubble level again to check for the level of the mount. Check both parallel and perpendicular levels to make sure it’s leveled. Adjust by tightening or loosening the screws to achieve proper level so that you’re able to go ahead.

Step 3 – Attaching the scope:

Your scope mount is now secure and ready for the rifle scope to be attached. Place the scope carefully on the mount rings, on equal and flat surfaces on both sides. Place the top of the scope rings and tighten the screws with the hex bit screwdriver to about 80%, in an X pattern. This helps keep the scope even. This is the final time where you can adjust eye relief of the scope.

ALSO SEE: What do Numbers Mean on a Rifle Scope?

Step 4 – Finalizing and leveling:

Level your scope by placing the bubble level on some flat knob or adjustment of the scope to check parallel and perpendicular levels. Once satisfied, tighten the screws of the mount rings in the same X pattern for proper tightening. Re-check the AR-15 for the last time for levels. Check the alignment of the reticle. This can be done by aligning the reticle to an object that it already been verified vertically by the bubble level.

Your AR-15 is ready to use with the rifle scope. Safe and happy shooting!

Into Long-Range Shooting? Here’s a guide for you “What Scope Do I Need for 300 Yards?“