I refinish guns as a hobby, I just finished my brother's older Ithaca M-37.

You need to do a little searching first...

1) Contact Remington about your stock. It sounds as if it is relatively new, and if that is the case talk to them about getting a replacement if the finish is that poor.

2) Get in touch with the technical staff to determine what your stock has in terms of (A) wood, (B) stain, and (C) clearcoat finish.

After you get those answers, you can proceed. Best bet is too remove the stock and forearm from the metal components, as you will want them to match when you are finished. You can go to a hardware store----or Lowe's/Home Depot---and get an adhesive remover (liquid or aerosol) to remove the tape gunk. Follow that with Acetone or mineral spirits---the wife's nail polish remover will also do the trick...

Next, pick up a finisher remover---last one I used I believe was made by Kleen and was an aerosol---to remove the polyurethane/shellac finish. The same stripper can then be reapplyed to remove any stain.

I'm not sure, but I believe Remington is similar to Ithaca, in that they use Walnut for their stocks/forearms and then just clearcoat. Therefore, it probably isn't stained. If you want it darker, I would try a Special Walnut or an Early American stain (Minwax). Dark Walnut will probably be almost black...

Best bet though, definitely contact Remington first...