I'm new to guns but will all of these 9mm pistol cartridges work in a S&W M&P 9mm?? http://en.wikipedia.org/wiki/9mm I just thought all 9mm ammo was alike. I don't remember any restrictions on the length of the bullet so seeing that article is really confusing to me. Can you guys help clear this up for me?? Should I be worried about the length of the bullets I buy?