When choosing Firenock lighted nocks you have an option to weight match the non lighted nocks to the lighted nocks. If not, there is roughly a 23 grain difference between the two that can result in lower impacted points at distances of 30 yards and beyond, and also change your front of center percentages.

There is a simulated weight that attaches to your nock just the same as the lighted nock that will make all of the nocks weigh the same.