Originally Posted by Cody
Just wanted to thank all of you guys for the help. Now I have a much better understanding of scopes than I've ever had before. Just one more question though...What do you mean by 30mm?
30mm is a measurement, just like inches. It can refer to the measurement of the main scope tube, the part the rings actually grab onto or the objective lens of the scope. Some scopes come in 1 inch diameter scope tubes and are good but 30mm is larger in diameter and area and will gather more light.
1" = 25.4mm diameter
30mm = 1.181 inches diameter
You might wonder why .181 inches might be better but you have to think of the area of the lens, those numbers there are simply daimeter.
30mm diameter tube = 706.858mm (27.829 inches) area
1 inch diameter tube = 506.707mm (19.949 inches) area
If you're hunting or long range shooting, go 30mm and dont look back is the common recommendation.
Oh and dont forget to thank your high school math teacher.