This is Carl, Rick Grimes's (the main character) son. Carl learned how to used a .22 Pistol at the age of 7, and at 8 his dad let him keep it. Although Rick's wife didn't like the idea of a seven year-old carrying around a gun, she let him, because duh, they're in a ZOMBIE APOCALYPSE!!
The whole team together
Lastly, a comic book reference, to see the character better.