The M6 was made in 22 Hornet/410 for the Air Force and had a 14" barrel. The later Springfield guns were made in 22lr/410, 22 magnum/410, and 22 hornet/410.
I had a Ruger 10/22 TD but sold it and kept on using the AR7 for the simple reason that it broke down smaller/more compact. It made it easier to store in a vehicle or my BUG kit that stays in my vehicle. That being said, of the three listed-AR7, M6 Scout, 10/22 TD-each has pros and cons so you have to decide what works best for you, but any of the three are great firearms