Boxer is pretty much correct.
I shy away from suggesting sanding because too many fellas will sand for profile, not finish. When I sand, it's just to clear the initial finish surface. Now, if your stock is a grey color due to caustic cleaners, chances are that it's just the 1/64th thick surface that is grey. If you were to sand that away, chances are good you'd find a more virgin surface. However, then you end up ruining cartouches or other feature.
So, to lighten the surface you can use Boxer's "B" or "C" suggestion. This is for more advanced finishers.
You can bleach with a number of items but they can be very unpredictable and bothersome. Even the 5% solution of Clorox will work but, again, unpredictably. If you want the stock to be back to 'normal', I would recommend that you go to your local home store and find the Kleanstrip brand wood bleaching kit. IT contains two water-clear, very inert looking vials. You mix equal amounts and then rag onto your wood a very wet coat. Here's the secret. You will see NO difference until you let that stock go overnight and dry completely. This is not an instant bleaching kit and, as so, it will be very gentle with the original pigments. I would recommend two applications. One on one night, dry, then another.
After that you will take a piece of 180 stearated paper (found in home stores anymore; it's dry lubricated sanding paper and is usually pink or orange or some of other color. It is NOT garnet paper which is the worst thing you can use) Using the paper you will oh-so-gently rub the surface only. Scrub too hard and you'll end up with grey wood again. Now you can do what you would with the stock. I never use anything by Minwax. It's not really a good material to color with. Rather I recommend using "Behlen" products. You can google them and find their "15 minute stain" which is nothing BUT stain, no oil or other finish unlike Minwax which is nothing more than a little dye with some thinned tung oil. That seals the surface after one coat. The Behlen product is strictly color only, allows you to adjust the depth of color you're looking for by doubling or removing coats, and then you seal with your tung or BLO. I use the commercial variant of the same stuff in my shop.
Sorry for the long answer. Actually this is a short answer. You can find a bunch of this information at another site I moderated for many years.
http://parallaxscurioandrelicfirear...stock-cleaning/CR-stock-cleaning#.VVDfuvlVhBc
There we have a strict rule that defines restoration from repair. Each rifle we own has a history that we want to preserve. The stickies at the top of that forum are chock full of information that I won't have to retype.
Rome