Yep, we used to fight over the Red tubes. I made many slingshots back in the day and rubber band guns also, but never made an automatic:).
Y’all must really be old as I am only 77 and don’t remember red inner tubes and all my sling shot bands were cut from 600 X 16 car tubes. Today I have 2 wrist rockets that I shoot marbles at what ever annoys me...