I had one that was twisted to the point that one of the oblique flats in the barrel channel was almost lined up with the bottom flat of the barrel, at the muzzle. Lots of attempts at wetting/clamping with barrel in place didn't do anything, the stock just kept springing back when the barrel came out. Plus I was fighting rust on the barrel.
I finally had to clamp the lock end of the stock upside down to the bench, without barrel, then used door shims under the tip end to put in almost 1/8 turn extra twist after wetting. I also gave it a few minutes of steam from a wallpaper steamer, just for good measure. I let it dry for a week, also for good measure, and when I removed the clamps I really expected it to spring all the way back just like before. IT DIDN'T!! I was thrilled. It wasn't perfect, but it was a WHOLE lot closer, and much easier to work with. the barrel would seat with just light finger pressure, and the pins held everything in place with no issue.
Don't know which direction yours is warped, but I think the trick on mine was going past 'straight' so that when it did spring back, it was 'almost' straight. I have also heard more recently that steam actually helps wood flex so that it will take a set after it cools and dries. I didn't know that at the time, but it worked.