From a practical standpoint, I have seen better arrow groups from nocks that fit as I just described, especially with broadheads. All this is really one of the main reasons our strings come with the .021-inch diameter serving instead of a larger size. I believe, for most shooters, it will yield a more accurate shot and be easier to tune. Of course, this all depends on the nocks a person is using, but for the most part our 20 strand BCY 8125 strings with .021-inch serving will produce the correct nock fit for most regular sized nocks such as Super-Uni nocks and large groove G and X Nocks.

As far as serving material goes, probably the best stuff out there for holding its shape is the BCY Halo in .019-inch diameter. However, Halo is a little more susceptible to separation, which is a definite negative. Some of the top shooters we have on staff use this center serving with great results. This diameter will provide even a little looser nock fit than the .021-inch material but it is still within the acceptable range. Our standard center serving is our exclusive X-Braid Plus, which also holds shape very well and does not have any separation issue.

Conclusion
You may think that something as mundane as nock fit cannot possibly matter when all you want to do is shoot a whitetail at 20 yards. You may be right about that, but if you are trying to shoot a mule deer at 50 yards, an antelope at 40 yards or win a local archery competition, everything matters--right down to the smallest details. One of the small details that can make a real difference in your shooting is nock fit.