Everyone seems pretty deadset in their ways with regards to testing. That is strange give that testing is an exercise in objectivity and objectively speaking, there are really good ways to test and really bad ways to test.
But be that as it may, it seems fairly well accepted that by the time one has adequately "tested" one's ammo, the lots are usually gone. So, another approach might be to simply focus on one or two things - for instance, the labeled velocity. Will your rifle shoot best with ammo in the 1050s, 1060s, or 1070s? Because that might be all the selecting ability you have. For instance, I did manage to test and find that my rifle really seems to be happiest at 1063 fps. That is ELEY's 1063, not what it measures out of my gun. So, when I order, knowing that ammo will be sold out in 1-3 days, I simply go for the Tenex that is closest to 1063. If I have to settle for 1064 or 65, so be it. But that is better than 1070s, for instance.
I do not worry about machine. I have yet to see or conduct a test that conclusively shows that it matters - your mileage may differ of course.
Brent