I figured this out today and haven’t seen it posted anywhere. Maybe it has and I’m late to the game. But to weight match my regular X nocks on the 5mm arrows to my Nockturnals there was a 16 grain difference. All I did was insert a regular 16 grain HIT into the nock end of the arrow then put on a regular nock and it’s perfect weight. Then if I ever want to remove it or put in a Nockturnal all I have to do it screw in a field point to the nock end and pull the insert out. Hope this helps someone cuz I was pulling my hair out trying to weight match with BBS and screws and wire anything I could find and this was way easier.