It won't need that if the one type of primer you use illustrates a clear statistically valid difference in performance between the two hole sizes. At that point, you can say it makes a difference, or that one primer wouldn't have shown one. If you want to know if it usually or always make a significant difference, then multiple primers and, preferably, multiple firearm testing would need to be engaged in to illustrate that.
I'll be interested to learn what the velocity mean and SD differences are.