Many rifles and shotguns feature hunting scopes or other sighting devices, so it's not unusual for it to seem like something's missing when you see one that doesn't have a scope. They are becoming more and more popular for handguns, too. The major reason is that they make hitting a distant target easier, even if the weapon has an iron sight built in. When you aim through a magnifying scope or use a red dot laser light it is easier to see your target and have a more accurate shot.

All rifle scopes feature a sizing system called a number range. These numbers refer to a hunting scope's magnification ranges and the diameter of its objective lens. For example, the first numbers of a 3-9x 40 hunting scope mean that it is a variable scope capable of showing objects three times closer than they would appear to be with the naked eye, but can go up to nine times the naked eye. The critical factor here is how low the magnification is rather than how high it is, because as the magnification increases, you willl get less light through the eyepiece.

The last number in the number range is the diameter of the objective lens, in millimeters. Hunting scopes typically have objective lenses with diameters of 40 to 45 millimeters. That's really all you need, even though the lenses of some of the more extreme models go up to 75 millimeters. The higher the objective lens number, the larger it will be and the more light you will get through the eyepiece. A delicate balance of magnification and objective lens diameter is what will give you the most detail and the most accurate shots.

The magnification range you choose depends on how much enlargement you need. Remember that the detail improves when you use a lower magnification, but you also need to think about whether you will be shooting at small targets from long distances. For example, you might choose a 3-9x 40 rscope for deer hunting, but you might want a 6-20x or an 8-25x variable rifle scope for pheasant or squirrel hunting because your targets will be far away.

A scope's objective lenses also can be variable or adjustable. External parallax adjustments can alter the diameter of variable objective hunting scopes. This can make a difference with hunting scopes with greater than 10x magnification. You won't generally find this feature on scopes with lower magnifications.

Lenses are usually waterproof and fog-proof. They also are coated with a single or multiple layers of coating to help reduce loss of light and glare. Generally speaking, the more layers of this coating, the sharper the contrast and the clearer the object's image will be. Hunting scope lenses that are fully multi-coated are generally seen as the best because they usually allow better light transmission and provide a sharper contrast.

Field of View is another term you will hear when looking at different hunting optics. This measurement refers to how many feet left to right you can see when you are looking through the scope. Typically, you will have about a 30 foot Field of View or FOV at a 100 yard distance on 3 times magnification. As the magnification goes down, the Field of View goes up. At 9 times magnification, the Field of View would only be about 14 feet.

Understanding the measurements of a rifle scope is important when choosing the best overall scope for the type of hunting you will be doing. As you can see, the measurements can make quite a difference in how precise your shots will be.