"C" means the barrel is ported. Porting is the "holes" in the end of the barrel on the models designated "C". Some people who shoot competitively find this helps with recoil or a follow-up shot. However, in a gun battle, it's going to do you no good. Muzzle flash in your eyes is not kewl at all. Especially if it's dark outside, you can be temporarily blinded. I am sure you can figure out why this is not a good thing. Basically, it "ports" the gasses which would normally come out of the front of the barrel upward, right in your line of sight. If it's not a carry gun, I wouldn't really fret it. Most potential gun battles (which would happen in a CCW situation,) are are going to occur at night--under low-light situations. (From my understanding 70%)....another GREAT reason for night sights... Hope this helps....
Greg