Jasco and Zip-Strip are similar. The older Zip-Strip was the best and most powerful. I think they had to weaken it down because of the strength and burning it caused. You will need very heavy duty non-chemical reacting rubber gloves. The current formulas are weaker and require much more time to soften the Browning finish, but will still burn your skin.
Wrap the stock in tin foil after applying the stripper to keep it moist. Go do some other work for a while, come back and reapply. Do this for a few hours or so and try to scrap some of the finish off with a dull edged putty knife. Make sure the edge is rounded off! After a while the finish will buckle and bunch up in front of the blade. Once this happens the remover starts to work better coming in from underneath the finish also. Use a toothbrush to clean the checkering out in a circular motion. This is a slow process that requires the formula to work. Sometimes even overnight works best. Once you have the finish completely removed flush, or wipe with lightly soaped hot water. Final flush with clean water. Do the same to the checkering to clean out. Let it dry for a week before you start working toward the finishing. Try not to get water down in the bolt hole.
Also remember that any glass bedding that was there will also be removed along with check fills and such. This should all be replaced before finishing.