I actually talked to a Kimber rep about this very subject. The Guardians are not reloadable. Apparently the original designs were supposed to be, But the BATFE stepped in and said that if the cartridges were removable then it would be considered a firearm. The Guardian actually uses a primer like device to launch the powder. The model with the pistol grip may take another upper unit, that I am not sure about. But at that point might as well carry two of the less expensive models that have no pistol grips.