"Messing" with the stock

[rjinga]

The previous owner was the person who cleaned the cosmoline off the rifle.  It looks like (I've sent a PM and I'm still waiting on a reply) he put some kind of polyurethane on the stock.  If he did, will it decrease its value if I lightly sand it and then reseal it with something else?

[Greasemonkey]

The value technically is gone, from a purist stand point, you cant reapply history, it's lost to sand paper and steel wool. Most likely the finish is tung oil or something similar, that seems to be the common refinish stuff the kiddies play with. If you want to knock the sheen down, hit it lightly with some 0000 steel wool and enjoy it.
As for stripping and refinishing a strip and refinish job, it can be done I guess.. LC is the stock guru, he might have some pointers.

[Loose}{Cannon]

I would leave it alone.  Why refinish a refinish? 

[Phosphorus32]

Agreed, I'd leave it alone. Sanding always makes the appearance of an honest beat up stock worse since it's so obvious, resulting in blurred stock serial numbers, more rounded edges, etc. Your pictures are rather low resolution but I don't see the "thick" appearance of polyurethane. Probably linseed oil or tung oil (or more likely the petroleum distillate diluted and drying-catalyst added versions commonly found on the market, e.g., boiled linseed oil, or the tung oil products found in hardware stores). In my opinion, tung oil and linseed oil are the least objectionable finishes used by those who feel compelled to try to shine up a beat up warhorse. Applying shellac over dents, gouges and scratches generally doesn't turn out well unless the blemishes are minimal.

[Loose}{Cannon]

I like the way it looks!

[newchi]

A beat up previously refinished stock is better than a newly refinished stock everytime.