Police say it happened at her grandparents' house in the 4000 block of Calver Court around 4:15 p.m.
Police say the young girl and other family members were visiting her grandfather's home when investigators say the girl wandered into a master bedroom, and found a revolver in a nightstand drawer.
They said while she was holding the handgun it discharged. The bullet struck her in the calf. Police say it was a through and through wound.
"It's very fortunate this child is going to recover, but it is possible the grandfather could face charges," said Fayetteville Lt. Todd Joyce. "No one set out with the intent for something like this to happen, so it is paramount that you store your firearm in a safe location in a manner to where a child could not access it."
Police investigators and crime scene officers spent several hours collecting evidence at the grandfather's home.
They are not releasing the name of the girl, or her grandfather -- saying their investigation continues.
Police did tell ABC11 that the grandfather is retired military, and was able to immediately render aide to his granddaughter while calling 911.
The child was transported to Cape Fear Valley Medical Center with non-life threatening injuries.