[Mengsk]

I usually go with the looking glass rifle. Unfortunately I have never attained the grenade launcher. However, early in the game you can get the marksman's pistol from the gunshop owner in Tarant. You need to pick pocket it, but if you have a fate point that works great. Nice pistol to have early in the game.
Whenever I fight zombies I like using the mechanized gun, oh so much fun!