Mayor weight sinks first. If the shank (in this case with lead) is heavier than the entire curve, the shank goes first to the bottom, turning the hook up. A hook without weight sinks with the curve below for that reason. Something very interesting here (I had thousands of discussions about it), when you add lead wraps -for ex.- tying nymphs, many times the fly will be riding on the bottom point up. So if you tie a beautiful nymph with a clear belly, dark back (as usual), will be not working as a natural. We are very lucky with this things, cause fish are mostly starving and they don't care. And are "political" discussions.