I just get a good paint stripper from the hardware store. I think what I have now is called EZ Strip. Old varnish usually comes off pretty easy. Then steam out any dents... I use a wet cloth and a soldering iron (you can even use your wife's iron, just don't get caught). After that I give the stock a couple of coats of Daley's Sea-Fin Teak Oil, inside and out... It is very thin and soaks into the stock easily and deeply sealing it and waterproofing it. It is made to finish sailboat decks and is popular hear in Washington for that, and it does get wet here!!!

Next I wet sand the stock with 320 grit wet / dry sand paper and more Daley's Sea Fin. Wet sand, and once it's tacky, gently wipe the extra off with a paper towel. This will fill all the pores in the wood and give you a stock that is as smooth as a baby's behind. It usually takes 3 or 4 coats wet sanded in. In the end you have a very smooth mat finished stock.

At this point, you can add a couple more very thin coats of SeaFin hand rubbed in and leave it this way, or you can apply whatever top coat you want over the SeaFin. Birchwood Casey Tru-oil works well and is readily available and Brownells has Pro Custom Oil stock finish that I like... Heck, you can even just give it a couple of coats of spar varnish if that's what you want....

JD

As JD said, ordinary paint or furniture stripper to get down to bare wood, but wear nitrile gloves (you can get hold of some of those, can't you? )

For finish, I have not yet found anything superior to the plain old tung oil that you turned me onto years ago. It ain't quick, but it sure is purty!

Let me look, I very likely have both as well as the 13 other items I just finished this evening. No nitrile gloves though.

You need some for cleaning guns anyway.

13 instead of 12 as I found one here.

Another trick for old varnish that I have used is carb cleaner. It's designed to dissolve varnish (dried up gas) from carbs. Not sure how it works on newer finishes, but it has worked well on several older stocks idea tried.

Ting oil has been suggested but I like boiled linseed oil. It's puts a wonderful sheen on wood and silly as it sounds, I love the smell! My old Ithaca 37 gets rubbed down with BLO every winter after bird season is over.