Finish choices vary, but the prep work is the most important step.
Use the small diameter dowel or rod as a sanding backer to sand in the tight curves around the grip cap and similar areas.
Success at any task falls heavily on preparation, and never more so than in refinishing a stock. To makeover a stock you'll need something to remove the old finish, sandpaper and sanding blocks, and the materials to produce a new finish. This assumes, of course, that you're dealing with a wood stock. Synthetic (fiberglass) stocks are a different matter and subject for another story, so here the term "synthetic" will now be used in reference to polyurethane-type finishes on wood stocks. There are four types of finishes you can remove/apply to your wood stock: lacquer, varnish, oil or synthetic.
Nothing that you might have on hand will touch a synthetic finish. No regular paint stripper, remover or softener will make an impression on it. Sanding it off would be a full-time job lasting weeks. However, for just such a project, Brownells (Dept. RS, 200 South Front St., Montezuma, IA 50171; 641/623-5401; www.brownells.com) has a synthetic finish stripper that will remove even the most impervious poly-based finishes. Apply it according to the instructions and your life will be much easier.
Removing lacquer or varnish finishes is easiest with general citrus-based paint strippers, which you can purchase at any hardware store. Brush it on, let it do its work, then blot it off. Don't rub, scrub or try to help, you'll just press the old finish down into the pores of the wood.
Oil finishes are much easier--go right to sanding. You don't have to remove the old finish completely, provided you're going to refinish with the same oil formula, or one close enough to it. Sanding is where the real work comes in, and it should be done on all stocks that have been stripped of their original finish. You'll need sandpaper of varying grit, the coarsest of which (about 320) is used simply to smooth out and hide dings and scratches. If you're sanding a new stock, 200 or 220 grit is a good starting point. The finest grit you'll probably need is 600, which allows for a very nice finish.
Now for the advice you're going to hate: When you sand with any grit, you must sand the entire stock. You can't just sand the scratches and lifted dents with 320, blend them in with 400 and 500 grit and then polish them off with 600. You won't be happy with the finished product and there are two reasons why. One, you'll be chasing the sanded "edges" of the blended areas across the whole stock, and two, you're more likely to create dished areas in the initially-sanded spots--dishes that will show when the stock is finished.
Without the sanding block, your fingertips would each create pressure points and sand an unattractive trough or dish in an otherwise flat surface.
You'll need a variety of sanding backers. Do not sand with just your hands; you'll round corners, muddy lines and dish the surface. The main backer should be a flat block of wood. With it, carefully work the large convex areas, like the butt and forearm. On tight corners such as the comb, use a stiff file as your backer. On the concave areas such as the grip, use a dense felt backer or a soft gum eraser as a backer. The slight give of these two backers lets the sandpaper conform to the curve, keeping you from creating flat areas. In very tight concave areas, use a section of dowel as a backer.
Always sand with the grain of the stock, never across it. In some locations, especially around the grip cap, you can't always follow the grain. Grit your teeth and follow the line of the stock. As you sand, regularly wipe the dust off and inspect your progress under good light. The temptation is to sand the easy areas a lot (forearm and buttstock), and give the hard areas (wrist, grip cap and cheekpiece) "just enough." Take the time to sand each area properly. Sanding must be done with the barreled action out of the stock, but with the buttplate or recoil pad and grip cap installed. This allows you to keep all surfaces flush and maintain an attractive fit and finish.
Each time you switch to a finer grit paper, you need to "whisker" the stock. Wood does not cut cleanly. At the microscopic level, the fibers are torn from the surface. A bent fiber that has been pressed into in the grain, or into a pore of the wood, may later rise up. To whisker the surface, gently steam the wood to raise the bent fibers, then sand them off. One method is to blot the stock with a wet rag, then steam the water with a heat source, such as a stove burner. A better method is to lay the wet rag across the stock and apply heat with a hot iron. With the whiskers lifted, start sanding with the next-finer grit sandpaper. Wood is fibrous, and everything that cuts it creates whiskers. You'll be whiskering your stock repeatedly, and right up to the point where you apply finish.
Applying a new finish
The two most difficult finishes to apply, oil and synthetic, also bring more to the finished product. The two easiest to apply, varnish and lacquer, will, however, do a fine job. . .on furniture. While a chest of drawers can stand up to decades of use in your bedroom, when is the last time yours got rained on? While easy to apply, lacquer and varnish finishes do not offer as much protection as oil or synthetics do. Many of my rifles have lacquer or varnish finishes, and I don't worry about them. But my replacement stocks or refinished or reshaped stocks get an oil finish.
Why not synthetic? First of all, you need much more equipment to apply a synthetic finish. Yes, you can apply synthetics from an aerosol can, but the cans are more for touch-up than total refinishing. I've seen nice work done with aerosols, but always by experienced painters. To properly spray a synthetic finish you need a compressor and spray gun, a dedicated spray room/booth and a respirator. Lacquer or varnish finish make you cough. Breathing the fumes from some synthetics can kill you.
If you elect to go with a lacquer or varnish finish, apply it in light, even coats. Once each coat is fully dry, rub the finish with a polishing compound, degrease and apply a new coat. Repeat until you're happy with the finish which, in my experience, may take as many as 10 applications.
Every surface and angle should be sanded carefully--and with the grain when possible--with the use of an appropriate size backer. The stock's entire surface must be sanded equally, or the finished product suffers. Sand in overlapping, unidirectional passes across the surface.
Synthetics are best applied in heavy coats. You'll want to put as heavy a coat as you can, but not so much that it sags or runs. (Hence the need for experience in spraying.) Repeated light coats bring with them the risk of oxidation which can become trapped between each layer, causing yellowing, or differential expansion between coats causing cracking. Oil finishes, despite the labor involved (and thus the cost when done by custom gunsmiths) are durable, can be touched-up easily and create a beautiful finish. Brownells has several oil finishes available, and you can make your own if you can find a custom riflesmith willing to offer up his favorite formula. The Brownells products come with instructions, which are lengthy but easy to understand.
The secret to achieving the best oil finish is in the application. In all, you want your first coat to be a thinner than usual mixture, and applied almost as a bath. The idea is to get the greatest penetration of the oil into the wood the first time, then build up your successive coats, progressing with more protective coats at or on the surface with the following applications. Once each coat is fully dry, it should be sanded to create an even surface for the next coat. Apply as many times as you can stand, as more coats make a more durable and beautiful finish. A proper oil finish can stand up to any weather you can, and keep on working.