That's cool that you figured that out. Some people can never learn how to do it and to others it comes naturally. As far as I go, I learned how to do it about 3 months after I started because all I ever listened to was old school Metallica. One thing you want to remember, though, is that James Hetfield down picks everything in "Master of Puppets". That takes a lot of practice and you'll always need to warm up before you can get to tempo. Trust me on this, by the way. I used to be a full on Metal Head.