Ug, that'd take a long time to explain...here's a quick rundown (made it up myself)
Completely disassemble
1. Mineral spirits all parts (lightly on wood)
2. Purple Power wood
3. Bake wood at a low temp, wipe as cosmoline seeps out
4. Repeat steps 2 and 3 until the wood is cosmo free and has no stain
5. Stain the wood with an alcohol based stain (I used
Chestnut's stain)
6. Wiped down with denatured alcohol to remove the stain, so that just a hint remains
7. Wet sand the stock (super, super, super fine sandpaper, mixed with denatured alcohol, several thousand grain sandpaper, can't remember exactly which
8. Spray shellac the stock (locks in any cosmo that may try to seep out later)
9. Tung oil (I used Gilipse or something like that) the stock with super fine wet sandpaper (super careful as even the smallest "grind" can obliterate makers marks and faint cartouches on the stock)
10. Apply as many coats of tung oil as desired. I used 2 and that was plenty for me, could have done 1 and a half. Just to how you like the feel of it. Buff it with an old T-shirt after each application. The more you add, the "stickier" it will feel. The buffing fixes this. Few coats leaves it not-shiney, lots of coats gives it a sheen.
11. Oil/CLP/etc. metal parts and reassemble
12. Apply some sort of wax (carnuba, kiwi, whatever) if you want. Gives it a shine or smoothness it may not have, depending on how some steps went
I prefer to keep them as in military like condition as possible, to preserve them. A lot of people use unique stains, fancy patterns, etc. I just try to keep it as true to the original as possible.