When in a zombie apocalypse, and you have a gun, you are going to need a LOT of ammo. Ammo is the main key in a gun. It's the only thing keeping zombies from eating your flesh. If you run out of ammo, and you dont have a melee weapon, then you are screwed.
Always make sure you have enough ammo to survive for a long time. and always look for a gun sho. They will always have ammo, unless someone has already been there. So keep an eye for any ammo not used in a house, gun shop, or anywhere else they could be.
Because it could save your life.