Magnification is perhaps the most important thing a scope does. At 500 yards, you will need a magnification of at least 5x, and you may want to go as high as 10x. Some of this depends on what you intend to shoot. If you are shooting small targets, you'll want a greater magnification to help you find them.

The answer is really simple: a 3-9X riflescope provides an additional level of magnification for every 100 feet, all the way out to 300 yards (900 feet). For many years, 300 yards was about the limit of what most big-game hunters considered to be an ethical shooting distance.

As a general rule, 1x magnification per 100 yards of distance has been the prescription for some time. By that standard, one could adequately take an 800 yard shot with an 8x rifle scope. On the contrary, if you've looked through a scope at 8x, you'll soon realize that more magnification is nice to have.