Personally, I prefer sandblasting to the glass beads. I think it mutes some of those minor milling /buffing marks better. You can then use KG guncoat's K-phos over the bear metal. you just simply spray it (with an airbrush or auto touch up sprayer) and let it dry. Gives you a medium grey finish. Then most spray a teflon or moly based paint over this and heat cure it (KG sells this also). This combo will give you about the toughest finish going. You can also use any of the high temp motor or grill paints over the K phos for an easier but less durable finish (of course its easier to touch up - just get out the can and spray!)
Just remember to use heat like Campy says to get out the grease or it can screw up your finish. I would add that carb cleaner, a brush and heat seem to work best for me. Its amazing how much grease I have had come out of a cleaned, and heated sandblasted rifle, so really be meticulous about the grease for a good finish.
Also, the grease and degreasing, equipement, and time can easily make this such a pain in the ass that its usually a better idea to send your rifle off. At least, that's what I end up saying everytime I get talked into doing it (but then again I'm a slow learner, a glutton for punishment and enjoy the satifaction of saying, I did that.).