Okay, we're going to go over caliber selection today. There are those that argue that a .45 is superior to everything because it makes a bigger hole. Others will make the claim that a 9mm will do any job and have a higher round count in the magazine. I've heard that anything that doesn't start with a 4 in the caliber department really isn't a gun. A claim was once made that .357 was king and if the cops had just kept their wheelguns, everything would have been fine.
Well, here's the rule of thumb we've lived by. Use a gun that fits your hand and is in a caliber you can safely handle for extended periods of time. No point in stocking up on a .50 AE when the gun that shoots it beats the crap out of your hands.
Stick with a caliber that is common. 9mm, .40 S&W, and .45acp were all used by police departments across the country before the end came. Chances are you'll find ammo almost everywhere thanks to local LEO's.
Caliber wars are stupid. A .22 will kill a zombie just as dead as a .45 will. If it works for you and you can hit a volleyball at fifty yards, you'll do fine. Use what you like and can find ammo for.