Brently, some years ago, someone did a study and determined that when shooting 3 under, the arrow nock can slide down the string when the arrow is fired, causing high misses. There were some slo-mo videos that showed this happening. The recommended precaution against this was to use a second string nock under the arrow which would prevent the arrow nock from sliding down the string.
Have you ever experienced anything like this, and if you haven’t, do you have any ideas as to how you have been able to avoid it? Do your self nocks grip the string, and if so, how tightly?