Hi have you tried what i do when removing old finishes , i get my cabinet scrapper out make sure it is a good quality and just try it on a small area , i find i scrap the finish off then steam out any dents or bumps and then use a ultra fine sandpaper to rub over , i then wash and clean it then another light rub then sanding sealer if needed then to the finish i want .
Just remember go easy no coarse snadpaper yo will knock far to much wood off , also remember you may need to re-size the butt pad a little i had a gun someone re-finished and the pad was very big they had done the sand it sand it get the colour out , i just took the butt pad off and re-sized .
Slow and steady wins the race