Moon nocks or flat nocks. What kind of nock should I shoot? The correct answer is whatever your crossbow manufacturer recommends. There is however, one exception to the rule. If your crossbow manufacture recommends you to shoot flat nocks, it will not hurt your crossbow to shoot an arrow with a moon nock, as long as you pay special attention to the nock orientation. The groove in the moon nock must sit horizontally when the arrow is sitting on the flight rail to allow proper alignment with the crossbow string. Failure to do so can result in a partial dry fire damaging your crossbow, or worse, possibly injuring yourself. On the flip side, if your crossbow manufacturer recommends you to shoot moon nocks, you do not want to shoot flat nocks. Flat nocks fired from a crossbow that requires moon nocks may result in a partial dry fire of your crossbow. This is because the string can jump over the flat nock, whereas the moon nock keeps the string centered in the back of the arrow, the full length of the power stroke. Please make sure to read your owners manual and use the recommended nock.