On the drop...
If the bell is resting on the heal of the palm. I initiate the drop by turning the pinky.. I sort of cast the bell to the fingers and catch it with the finger lock. Now, my hand isn't off the bell, but I'm not actively gripping it on the drop until the finger lock. It's not a strong "cast" or throw. But, I try to make the bell jump to my fingers to reduce the friction on the palm. Not sure if that makes sense.
What I'm not doing is flipping the bell over the top of my hand and then trying to finger lock..That would create a lot of friction on the hand because the bell would be rubbing the hand.
What you should do is cast it that it creates a slight arc (not drop straight down). ON the drop, you fold at the hips and follow the bell (So that you get a good swing back between your legs..pendulum effect). This also helps reduce the stress on the grip. This means that you don't stay up right; you fold more at the hips. If you do this, the bell won't pull or drag the hand and arm down.
Valery's videos are some of the best to watch. I can't get to youtube right now, but he has snatch set with a 24kg bell that is good to watch.
Hope this helps.