In your experience if it shoots good at

[L. Cooper]

The use of 100 yards as a "measure" of accuracy is just a convention for comparison, and the distance seems about right for practicality of range construction. It is easy to see with a good scope where you're hitting, and it's not too far to walk repeatedly during a session.

But the truth is that longer distances reveal more about the accuracy, or lack of it, that your load and rifle will produce. There is also no substitute for shooting at very long range to prove what is going on, and for the practice it provides.

Having said that, a good group at 75 will most likely be a good group at 100 or even 300 yards. You just can't be certain of anything without actually shooting at those ranges. A comparison of different loads at 75 yards would certainly have validity at 75 yards.