So this is the form that I'm pretty ok with right now. It's repeatable, accurate, and not stressing my knees or anything, but I'm to the point where I honestly don't know what to tweak. I feel like I'm getting the disc really close to my body and have good wrist extension. I'm getting consistent, audible snap on basically all my discs, but still can't really break 420 with any real consistency. I'm trying too damn hard in this video, but I'd been playing all day and was just tired and trying to get some stuff on film. What I can see is that I still need to get my shoulders squared to the basket faster, and that I'm coming off my chest with the disc too quickly, but I have a hard time thinking that is the only difference between 420 and 600. I have a slight nose-up problem as well, but that may end up being permanent due to my arthritis and carpal tunnel in my wrists. Anyway, any help you can offer would be great. Thanks!
Oh and for the record the discs are teebirds, a leopard, and two destroyers on anhyzer d lines. I really only use them for fieldwork. I get way more control from my TBs.