I can tell you for a fact, that the BT-99 grip will not fit a BT-100!!!
If you want a PFS grip for your BT-100? You will have to get a custom made grip. There never has been, nor will there ever be a grip made for the BT-100. Just not enough out there to warrant the cost of making the template to make a run of these grips. Good Luck to Ya. break em all Jeff