I did the math on this afew years ago and am going from memory and at my age that`s not awalys a good thing. I do rember for sure thr I was totally suprised at the reuslts, but as I rember the max. effective range gain of a 3 1/2 in. 12 ga over a 3 in 12 ga was less than 5 yrds. With the extra cost of ammo and the extra recoil I desided to stick with a 3 in gun.