You need to find an NRA Training Counsellor. James Heath is not a Training Counselor.
Once you are an NRA Certified Instuctor, you can take RSO by home study.
BSA Rules (if they haven't changed them) recently are...
Cub Scouts can only shoot BB guns and only at Cub Camp under certain rules. No Cub Shooting is allowed at the pack level.
Boy Scouts can only shoot .22's (single shot - loading the magazine is not allowed, no tubular magazines or semi-autos), air rifles, muzzleloaders and shotguns. No handguns. You must be an NRA Certified Instructor to be a merit badge counsellor for Rifle Shooting or Shotgun Shooting merit badges. (I'm a merit badge counselor for Rifle Shooting). To supervise scouts on the range you must be an RSO.
Guns and Firearms
Varsity Scouts are the same rules.
Venture Scouts may shoot handguns and all rifles (not just air rifles and .22's), under similar rules, but they must first take the NRA Basic Pistol Course.