If all screws are removed and all else fails, put the the entire gun in the freezer at least overnight. Then rap it swift and sharp with a wooden or rubber mallet. If you are trying to salvage the stock you may have to put a piece of thick cow hide between the mallet and stock. If that does not work refreeze. Then if you have a heat gun, heat the stock only from the bottom side, especially the recoil lug area . It needs to be heated as fast as possible, but do not heat the metal, keep that as cold as possible. Then rap it again with mallet.
P.S. Not responsible for a broken stock, yes some guys have glued the action into the stock, these can be a bearcat.
Good Luck.
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The good Lord gives us "Life" a "Window Of Opportunity" what we do with this opportunity, defines who we are and what we become.