Has he got ANY experience with guns or is this just one of those "I wanna be cool and carry too" scenarios? If you don't have any luck convincing him to stay away from guns, then the other positive influence you could have on him would be to take him shooting and teach him some gun safety. Maybe even take a course or two with him. Reinforce proper handling, respect for the weapon, safe practices, etc. Then if he has a raging fit, he will hopefully remember all the good things you did for him and wont shoot you in the face.