At 7 years old that is too young for a speargun. Kids don't understand the consequences of their actions, they think only of the immediate "now" rather than a chain of events in terms "if I do this then what will happen next"? Build him a toy gun that looks the part, not the real thing. If he had an accident then the responsible adult takes the fall, it is not worth the risk for either him or yourself!
These are good points. And I would not hand my kids a hunting weapon at 7. But I don't feel strongly I should decide it for someone else. I would feel even worse if the father handed him an adult size gun and he had an accident. I think it could be valuable to expose the child this early IF properly trained, and with size specific speargun.
How young do people start with bow and arrow? 22 riffles? B'B guns?
I was considering a rubber tip until he grows into it.
-DB