Kind of the bigger the lense is the more field of view you will have and the more light it will pick up... bad news is the larger the lense the further up you have to mount your optics from the centerline of the barrel which isn't a huge ordeal but the further they r mounted off there centerlines the more range will determin bullet impact... basiclyy if you mount a scope 4" center line to center line at 50 yds you will be dead on if that is your zero range but at 10yds it will be nearly 4" low

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07/SOT2
NRA Instructor