What's the right ammunition for your EDC / home-defense gun? Self-defense ammo should be RELIABLE, have proper PENETRATION, and must be ACCURATE. It has to feed properly in your gun and go "bang!" every time you pull the trigger! To effectively stop an attacker, the bullet has to penetrate to the vital organs, but it should not over-penetrate. Most self-defense ammo has hollow point bullets that expand on impact, creating a larger bullet surface area for added punch and slowing them down for a lower risk of over-penetration. Don't fixate on expansion; it's more important that your ammo is reliable and penetrates to the vital organs. Less expensive full-metal jacket (FMJ) ammo, or to use an old military term, "ball" ammo is good for range practice. Even a lower-grade defensive ammo will be more effective than high-end ball ammo. Defensive ammo tends to be more powerful and have more recoil than ball ammo, so it pays spend a little range time practicing with it. How much ammo do you need? Jeff has some advice.