Hornady Zombie Max Ammo. Hey... I didn't make this up. It is on their website. If you feel we may be facing a possible zombie apocalypse, you may want to visit Hornady.
After you stock up on Zombie Max Ammo, be sure to pick up some Zombie Targets at 2A Gear. After all, you can't expect to have success during a zombie apocalypse without a little training beforehand.