We go over the most popular pistol cartridges:

• .22 LR: super small round, not suitable for self-defense
• .380: bigger, but best for backup guns
• 9mm: aka 9x19mm, 9mm Luger, 9mm Parabellum
• .45 ACP: big slow bullet
• .38 Special: standard revolver round
• .357 Magnum: souped-up .38 Special with longer casing and more gunpowder

And of course...some rifle rounds:

• .223/5.56: AR-15 round
• 7.62x39mm: AK-47 round
• 7.62x51mm/.308: Larger NATO round
• .50 BMG: it's big