I think I know why it broke on you. Trying to spread it wide enough to not scar the stock as you slide it off. What I do is to loosen the screw and then slip the flat screwdriver blade between the metal down by the screw holes in the bottom of it and give the screwdriver a 90 deg turn which spreads the halves wide enough to easily slip it off, but not wide enough to break. Once the screwdriver is in place in it, it can be slipped off one handed just by holding the screwdriver and no scarring to the stock. Reassembly is a reversal of the technique.
FWIW, just in case you decide to continue using it.