Metal without a pick.
Do your fingernails chip at all? I do acoustic finger picking and this is a huge problem for me. I usually go for a stage of a couple of weeks until my nails are completely fucked and then I cut them off. I then have to wait until my fingernails grow again. I can only amagine what would happen if you try alternate picking.
You should check out John Butler I've seen him do some pretty mean tremolo style picking with his index finger but his fingernails are long and thick.
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