Easiest way is use paint stripper. Wear heavy rubber gloves, goggles . Stuff burns like heck if you get it on your skin. brush a thin coating on stock(after you remove all the metal) Let it sit for recommended time on can. Use lots of paper towels ,wipe off. You may need to do this a few times until you are down to bare wood. I have found that medium steel wool or green scrub pads help after the 2 nd application. Rinse with water but do not soak it. when wood is dry,lightly sand with 150-250 grit sandpaper and refinish with your choice of finish
Easy way is to purchase a can of full strength Easy Off oven cleaner. Remove all metal parts from stock, put on rubber gloves and work in well ventilated area, spray stock with easy off and let foam till done. Then wipe off with damp sponge and repeat a second time if needed. Let dry and lightly steel wool it. (Reminder)Doesn't work well on stocks that have the newer plastic coatings, that's where the sandpaper comes in handy.