I don’t know… seems like a useless measurement. Ok, it’s checking neck tension while you seat the bullet, but you can’t change it. The neck tension will be what it is. You know have loaded rounds. If the neck tensions are different, there is nothing you can do. Save for grouping similar tension cartridges together. And sure, I guess that is the point. Although, besides being a whole new set of grouped together rounds for testing, how is the reloader going to copy the results? As I said, the neck tension is what it is.