I can easily get these 90 degrees. And i can get a full FS half cab (Or would it be a BS half cab? It's the same way rotating as if it was a BS 180, just fakie)

But when i get the full 180 my front foot slips off the front (As in side, not nose) of the board. How am i supposed to stop this?

Or any general advice for BS 180's would be nice. They feel so unnatural.

i snapped my top ply on a flatground bs 180 on saturday; i really need to learn these properly too.

apparently, you just have to give a swing of the shoulders, then pop as they begin to make the 180 turn.
i suppose it's practising, but god, they're fucking inconsistant.