Actually thinking that exposing a child to adult things will some how teach them to alter their gun related trajectory is not very smart. Children's brains are not even fully development at 5 years old. There is no way to know which way exposing a child to guns at an early age has to them being a responsible gun owner. The kid who killed all those children in Newtown CT used guns at an early age and that didn't seem to change his behavior.
Personally, I think there should be a age limit when it comes to children shooting a gun. What that age is I don't know but 5 is way too young. Would we allow a five year old to drive with adult supervision. You could teach your kid all the safety you want about guns but they do not have the cognitive ability to make sound decisions at that age.