for me it depends on the jaw surface and possibly the angle. The rawhide (and I mean rawhide not tanned leather) grips the angles of a rough cut flint better and the lead holds it down firmer with out wiggle. On a smooth or "cut" flint I would, and have, used either. I wet the rawhide, affix/ tighten, let dry and keep it tight as needed. You can change the flint angle some also by varying the thickness of both the lead and rawhide front or back. Hell, try it either or both ways and see what works best for you. We all have opinions as you will see..........PS keeping the front edge of the flint square/aligned flat across the frizzen will help keep the flint from trying to twist if one edge or the other hits first, and extends life of your flint. Sure hope I've made some sense here......
