Hi Cameron!
I assume that you are shooting 10 meter air rifle? If you are, and you are experiencing blurring during the sighting process, you are in dire need of a set of shooting frames. What is your correction in the sighting eye? This will determine what diameter lens that you will be able to use. I would also highly recommend that if you do indeed get a pair of shooting frames that you have the lens edge coated black. This is a must to prevent light from entering the side of the lens and causing distortion. I have a vast amount of experience with shooting frames so I can help you get off on the right foot. You need to see the target crystal clear and settle for nothing less!
I trust that I have helped you.