I bent a stock of a Tulle musket some time ago to increase the drop at the comb and heel, so that the gun didn't crack your cheek when fired. I used Canola cooking oil, heated on a hot plate in the shop 'til almost smoking heat. The musket, lock removed, was clamped over a 2 x 4 piece of lumber to create clearance for a catch-tray for the oil, a couple shop cloths tie strapped to the wrist. I cut a wedge of maple to insert under the heel, marking it before I started to see where I started out, and how much deflection I had added when done.
When the oil was hot, I used a stainless steel ladle to pour the hot oil onto the cloth wrap, allowing to to flow into the pan beneath, and then returned the oil to the pot on a regular basis. I kept up with this procedure until I could easily push the wedge further under the heel, and continued until I went past the spot where I wanted to end up, because the wood will want to straighten back out some when it is cold.
When the wood had cooled, I removed the wedge, the pan, and the cloth wrap. the oil finish on the stock was not altered in any way, much to my surprise. On bare wood, you will need to de-grease, so that stain and finish may be applied. Acetone (wear rubber gloves) will work, as will Trisodium Phosphate (TSP). Both are hard on skin, and acetone causes cancer, so protect yourself.
Today is October 2nd, 2020, and I have tried to replace the pirated photos, but have been unsuccessful. I managed to delete the Photobucket iamges and tried to use the "add image to post' link, but it refused to open for me. Sorry.
Final result...