Mineral Spirits will remove Linseed Oil, but won't remove it rapidly or remove any that's down in the wood. And any BLO (boiled linseed oil) that gets removed can be put right back. Try a good wipedown with the mineral spirits, let the stock dry, and then take a few drops of BLO on your hands and rub it on the stock. See how that looks. It should give you a nice satiny shine. If that doesn't look anything like you want, and is still too dark, then maybe you want to consider refinishing it. The dark color on a lot of old stocks will be where the hands were on it, and is likely due to penetration of various oils (gun oil on the shooter's hands, for instance) that darkened the wood. I don't know if those oils will come out to your satisfaction.
As for the acetone, yes that should dissolve any oils and greases, and will do it much faster than mineral spirits, which might make it the better choice for removing deep down grime. Good luck, but if you decide to refinish, let us know. We have suggestions and details for you on that.
