A compressed gas gun is provided, wherein the body houses a firing assembly and an internal, built-in projectile feed mechanism. The projectile feed mechanism is preferably formed as a rear or butt stock of the compressed gas gun. The projectile feed mechanism preferably feeds projectiles to the firing assembly via a feed ramp having an S-shaped transition portion. The compressed gas gun preferably includes a removable top feed rail assembly that can be removed to expose the interior of the compressed gas gun body for field stripping. Central control circuitry is preferably provided for controlling both the firing assembly and the projectile feed mechanism.