@weealf I watched your videos. I think you should add some tweaks till it feels easier. It’s possible your motion needs to go more out than down.
Have you seen this yet?
The whole video is worth watching but I’ve got it cued up to where the down-picking guys are shown. Hetfield to me looks like his hand is traveling away (“out”) from the body. Not sure if it’s a bad analogy but more the motion you’d make when you throw a Frisbee??? That’s sort of how I’m doing it and I fired the track right up and played along, no issues.
Well ok, some issues lol! But I just pulled the guitar up, no warm up or anything. I’m sure if I spent even an hour’s time, broken up into small chunks, I’d have dusted off. That’s not at all a brag, to me this isn’t hard and Troy says the very same thing in his video. When players are doing things we’re not able to do, it’s just because they’re doing it differently than we are. In other words, we’re working harder. So I’d say keep searching for a more efficient motion. Yours is close. You couldn’t hit 90% if it was wrong. Tweak grip/angle etc until you get something that feels “spring like”. To me this is almost floppy, elastic motion.
EDIT:
I just thought of something. Technically, you can economy pick part of it, yet still do all down picks. The main pattern is 2 palm muted open E’s, then the power chord, which for part of the riff happens on the A/D strings. So you could pick down on the first palm muted E (clear the strings to reset for the next down stroke) Down on the second palm muted E, without any need to clear the strings and reset, just continue with that down stroke and hit the power chord? maybe??? lol!
Just a thought, not sure if that would create “2 things to have to learn” where just one technique worked before.
Biggest tip I can give is you want the motion of the strum to be as “vertical” as possible. It should be close to a door knocking motion. You’ll have to supinate the proper amount to make that happen. For whatever reason, a 3 finger grip seems to help (Hetfield does this too).
Best of luck! You’re close!