I never tried to take the floor out, as the top was already open. On mine the floor is metal, including the hoppers, with a plastic "door piece" sliding above it, and springs at both ends. There is a tab on each side that opens the doors when it's pushed by the unloading ramp.
My car is extra heavy, as it's filled with lead shot, and has been for over 40 years! Yes, if I open the doors, the shot falls out...