Typically when you build your arrows, or get new pre built arrows, the first thing most experienced archers do is check the nock fit on the string.
A good rule of thumb is to nock the arrow on the string and let it hang from its own weight. It should stay attached to the string and not fall off. Then gently tap the string with your hand, and it should drop free. That is how I gage the perfect nock fit…
How you go about matching your arrow nock of choice to the string serving is up to you. A lot of these plastic nocks can easily be tightened or opened up slightly with a hair dryer to warm them up without damaging the nock. But I personally think it’s best to match the serving size to your nocks…. Use a different serving, or a different nock….
If they are a bit tight on a new string, that’s fine… it won’t take long to shoot in your string and the serving will compress a bit….. It’s all part of the game….
Tell your string builder what nocks you are using, or send him one… Done deal…
Take 2 aspirin and call your string builder in the morning..