Gary, I use small wood wedges and clamps along with the heat(heat gun) to correct twist in limbs. When I'm making heat corrections I use cooking oil along with the heat as not to scorch the wood but I believe it also helps hold the heat longer and distribute the heat better. After all of the heat corrections are complete I use heat(heat gun) without oil and scorch the belly well, while on a form to add reflex to the stave. This scorching also adds to the compression strength of the wood. At this point try not to allow the scorching to wrap around the stave. Scorched back can be disastrous.