How to remove polyurethane from a rifle stock

[ghost07]

I have a model 1895 Chilean Mauser that is in really good condition and numbers matching except for the bolt. The bad thing about it is that somebody put a high gloss finish on the stock which looks hideous. I want to remove it, hopefully without damaging the original finish, and put several coats of BLO on it. I have tried mineral spirits, lacquer thinner, denatured alcohol and acetone and nothing phases that high gloss finish. I’m guessing it’s high gloss polyurethane. Does anyone have any idea on how to get that gloss finish off?