Even better to do:
Get some amber shellac, cut it pretty thin with alcohol as directed on the can, and get some 0000 steel wool.
Dip the steel wool into the shellac and wipe entire stock. The alcohol will soften the existing shellac and the new shellac will also cover. It may take a bit and some elbow grease but once it starts to soften, it'll go pretty easy. This will give a very even coat that also evens out any shellac color variances.
I've done alot of Mosins this way. After the shellac is evened out, I like to wipe down one last time with a rag lightly coated in the shellac. You're adding very little new shellac and restoring the existing stock. It's quick and very effective. It may sound dumb, but be sure to remove the barrelled receiver before working on the stock
Shoot me a private message if you want me to give you a great site for stock cleaning and restoring---not refinishing. I don't want to "advertise" another forum here