Properly heated, wood becomes quite elastic. Sure there are limitations as to whether, or how far, a piece can be bent depending on wood thickness, grain and ring orientation, wood species, and more. Heat bent wood is used in industry for a lot of products and maintains its new shape indefinitely. It won't unbend itself, unless enough heat wasn't used, or used long enough to penetrate, or it wasn't held/clamped until cooled. There's usually a little bit of 'springback' when clamps are removed that needs accounted for, no biggie. If I can bend osage, one of the toughest woods around, from straight, into a full recurve bow in just a few inches, I'm confident many otherwise good quality maple gun stocks can be straightened enough to be made useful again.
I'm pretty sure I'm going to have to do it to a blank or two I have here in order to use them, and when I do I'll post it here.