I converted a Mercury Sable with a R12 system to R134a and I can say done correctly it was as cool or cooler than the R12.
As for the BB gun I don't think it was out for long about 2 or 3 year, it was probably a liability nightmare. Back then I don't think anyone had ever heard of Global Warming or what freon would do to the environment so we were blissfully ignorant on what we were doing.