No one else specifically mentioned this - it's something I should have known, but had to remind myself of the hard, painful way (twice) - when shooting top-lever rifles with significant recoil, DO NOT leave your thumb on the top of the tang. It doesn't matter with bolt guns, or when the recoil is less strenuous, but the .500 NE WILL bite you, if you forget to wrap your thumb around the top of the grip. Mikey's Rule of Thumb!
mhb - Mike