i hate the M92(if nobody has guessed that yet) but as for the whole 9mm vs .45ACP debate here is my answer...

http://www.lcompanyranger.com/usweapons/m79suchke.jpg

forget either one. 40mm buckshot for the win.

the M79 40mm grenade launcher with behive anti-personnel rounds! I love those damn things. any weapon that will turn your enemy into a fine red mist is a wonderful thing. You just have to make sure you don't let anything you want to not destroy be in your cone of fire!