5.56 Nato, 12.5" Carbine Length Barrel. I rarely fired it but not to worry I have a spare 12.5" barrel and carbine length gas tube I took off it's twin with it. I have no need of the spare barrel or gas tubes and they'll be more trouble to sell than they're worth. This is a complete Aero Precision Upper and Lower, both are M4E1. The handguard is a 12" Atlas S-One and it has an A2 Flash Hider on the muzzle. Magpul Storage Pistol Grip and FDE Charging Handle. 

Located in Chapel Hill, TN. Cash Only. I won't meet you anywhere, you have to come here and get it.