If it's a Russian Capture and you want the gunk off it, go with Acetone or with Circa 1850 stripper. Both will remove any finish or shellac, but they will leave the patina (colouring) intact, and they won't mess with the grain.
Stay FAR away from any method involving copious amounts of water... it just isn't good to let soak into your stock. I'd also stay away from Easy Off oven cleaner as well.
I *believe* the 98 stocks were finished with boiled linseed oil, don't quote me on that. Add lots of thin coats for a nice finish.
Just to make sure, you ARE working with a solid wood stock, and not a laminate, right?
If the rifle isn't Russian Capture, does it *need* to be refinished?