my go to solution for removing most finishes is MEK (methyl ethyl ketone), the solvent utilized in making fiberglass.
35 years ago had a browning rifle with the typical "alligator" cracking of the factory double-based urethane finish. lived next door to an engineer who worked for a large petrochem plant, and he brought me small samples of every solvent they used/produced - none of them would touch the stuff.
ultimately had someone tell me to try mek, and sourced some from a fiberglass boat repairman. it simply melted the finish away with little time or effort. it can be found at any paint company stores.
my method is a small disposable pan (tinfoil pie plate will do), and a cheap paintbrush, always work outside (this stuff is quite nasty) and wear chemical resistant gloves, eye protection, etc. I hold the stock upright in the pan and start at the highest point. simply continue to brush the solvent onto the finish until it is gone. as it runs down the lower areas it will start the process before you reach them.
in my experience, 15-20 minutes will take care of virtually any finish. the volatility of mek insures that it will not soak into the wood (it evaporates extremely quickly), so you are left with a bone-dry surface without any hazards related to chipping/sanding/etc.
happy labor day to all!
tom
