Quality of Image
One of the biggest factors that you need to pay attention to when buying a rifle scope is the image quality. Always keep in mind that quality scopes allow minimal to zero reticle movements. If the image is too tattered or hazy when you magnify it, it will be very difficult for you to make an accurate shot. Hence, it is important to buy first class optics so you can ensure quality image and it will reflect maximum possible light.
Another factor you need to consider is magnification. Magnification is very important in long range shooting or hunting where powerful scope is very crucial especially for a powerful gun. This is more helpful if you are shooting over a long range target, Your magnification should also be quality and first class.
The capability of adjustment of the scope is another factor to pay attention to. Generally, good scope will allow nil reticle. Hence, you should be able to remove any error due to parallax. As a rule of thumb, you will be able to know when there is a light change in the position of your eyes. In addition, most of the scopes of rifle that you can find in the market will not indicate any signs of parallax error for a distance of up to one hundred yards.
Last but definitely not the least is the mount of the scope. Tho it is not totally related with your scope, the mount of your rifle is an important consideration as well. Usually, if you mount is not appropriate, there will be a lot of problems that you will encounter along the way because of the inadequate movements. If you check some information online on how to choose a rifle scope for deer hunting or any other activities, mount would always be one of the biggest factors to consider.