I think you missed this one Drtybkr he asked If he was OPEN Carrying. That gives reasonable suspicion to investigate and you can be asked for your permit, and you must show it. Other option is Obstruction!!! Don't want to go there. Not saying I agree totally but that is the law.
While openly carrying the license has always been an element of the offense in Georgia law. You can not detain someone for just the gun, there has to be something more. The 4th Amendment requires RS of criminal activity to detain......you can ask but not demand.