Muttonbuster try going down up down up down up, over and over again and try to mix it up between like 16th note beats and 32nd beats, its pretty easy once u get going. Start out slow then work your way up faster and faster.

You have to use upstrokes to play 16ths unless you're at a very slow tempo for punk. Down strokes only on 16ths is like 32nds alternate picking. at 120 bpm (most punk is at least that fast) 32nds are 8 notes per second!! most beginners struggle to get 16ths at 120, which is 4/sec. if you get to more than about 15/sec. it sounds like a blur.

But there’s not really a specific technique u could use, just practice doing what i already suggested and go for it.

Good luck! :)
Vince Rudd.