If you have the bottom curve of your stock all set, then you need to form the guard to it.
If your stock profile isn't done, then don't bend the guard yet.
For my vise, which I use as a press:
I make up a vee block out of maple, and put the bow, for example, across the vee. Then take a finger, also of maple, and press that in the middle of the guard bow that is resting on the points of the vee. As I tighten the vise, I can watch the bow bend, and have a lot of control WHERE I want to bend, and how much.
Sometimes you need to bend right where the grip rail meets the bow. That's where the above method works really well. You might have to make custom fingers or nests to get into tight areas, but that's easily done with scrap wood and a saw.
