Alright so I wanna play Master of Puppets by Metallica but the downpick is so fast. How do you suggest I build up my speed or is there a particular technique. I have been playing for like 1.5 years and can alternate pick notes at like 100 bpm. How do I get downpicking that fast.

Edit: I can tremolo pick much faster by 100 bpm I am talking chromatic.
well i havnt tried it but from what i have gathered from others is to use a metronome
just downpick as fast as you can for as long as you can each day, thatll make you faster at it and youll be able to do it longer
umm im a pretty fast down picker cuz i spent the first ...year maybe? only downpicking ......so ya.....im guessing.....just like on songs you would alternate pick....try to only downpick.....and basially just practice it for as long as u can.......( for soem reason i thought about this........downpicking is basically half as fast as alternate picking.......so if you were a faster alternate picker.....would you not be somewhat faster at downpicking.....just a thought)