So I'm in the market for a Sub 2000, a folding carbine with a 16" barrel, it is available in 9mm and .40 rounds. For self defense, with the possibility of turning light cover, such as a car door, into concealment, which round offers the best protection? If the protection offered from both is similar is their a reason to go one way or another? I figure the 9mm would be a bit easier to shoot, but I'm a pretty big guy and don't think it would make much of a difference. Everyone says 9mm is cheaper, yes I know, but this is a self defense weapon. Plus I'm living in an urban/semi-urban environment. I just read this thread on the subject: http://thefiringline.com/forums/showthread.php?t=435504
But for my needs as a self defense weapon what would be the prefered caliber? Or is their little difference when being shot out of a rifle?