I have shot with a couple of pro's, one of which was a two time world champion, who commonly rotated the nocks on their ACC's so the arrow wouldn't take a set from flexing the exact same way all the time. They also replaced their nocks quite often so the fit of the throat and the part inserted into the shaft remained consistantly snug. BTW, the fl. green nocks are the toughest, not as soft as the other colors. They remain the tightest fitting.