I tried the metal nock too, a couple of years ago, but I was using a scott mongoose release and I had the release hang up on the nock when released a couple of different times. Talk about getting your attention, pull the trigger and nothing happens until about the time you wonder WTF, it would release. Luckfully, both times I was acutally pointing my bow down slightly so the arrow didn't just go sailing into my neighbors yard[] Thast was it for me, been using a string loop ever since.