Anybody Familiar with a Crosman Model 111 Pistol

My buddy dug out an old Crosman Model 111 pellet pistol, that belonged to his grandfather. Does anyone know how you fill these? I have read that they need a bulk fill CO2 adapter and have seen pictures of what they look like. He said he had a “tube” that went along with it but doesn’t know where it is now. I am guessing that was the CO2 tank. does anyone know if they make retro tanks?