You can not go wrong with the S&W 15 22. There are fine little rifles and accurate. I would be sure to get one with the flat top on it so you can mount other optics sights and etc. I think they all come that way but not sure. It would be a great rifle for you and your son to go to the range and shoot also teaching him safe gun handling and shooting basics.
At 8 he is not too young to begin teaching him to shoot a real gun!
The Constitution is not an instrument for the Government to restrain the people. It is an instrument for the people to restrain the Government!
“Americans have the right and advantage of being armed. Unlike the people of other countries, whose leaders are afraid to trust them with arms.”
James Madison. Author of the 2nd Amendment