[Mike Rockhill]

I had a similar appearing finish on a rifle (judging by the way its peeling off, and its color on the metal) and the correct solvent for it was mineral spirits. I would steer clear of the zipstrips and other solve all stuff as it will probably eat the original finish off too. You just need to zero in on what solvent is correct for the material on the stock, which in many cases will not remove the original finish underneath. You are going to have to test it on the metal first, to see if it will remove the stuff, then try a small part of the stock to remove the stuff and see how it affects the original finish. I wouldn't slop it on either it is a labor of love, done with a clean cotton cloth dampened in the solvent to be used. I would try mineral spirits first.

 

[Mike Rockhill]

If it really is laquer (which has come to be a generic term) then you would use laquer thinner. I think there is a problem then, the original urushi is a laquer of sorts and would also be affected.