It turns out my 10/22 is a very picky eater, at least with Federal Champion ammunition. But give it what it wants, and it can perform vey well.
It seems to like the .0415" rim thickness much better than the others.
Unfortunately, that's the least-common size I've encountered in my first few hundred rounds of checking. But some other rifle might favor one of the other flavors. I'll do some quick checking with the CZ 453 and 455 soon. Now that I have a supply of sized-and-sorted ammo, things can move faster.
Testing with other combinations, including dog-and-cat mixed old ammo, left me with lots of contrary results.
Aside from learning how rewarding it is to feed my finicky Ruger its favorite snack, I've come to the conclusion that so many variables are involved in firing a round that some will cancel out the others, randomly. Since every individual variable probably presents itself as a bell-curve distribution of arbitrary x-and-y dimensions, stack a dozen or so on top of each other, and you get a roughly "round" group with lots of what I thought were my flyers thrown in. Cut down on some of the variables, and a simpler pattern begins to appear, or at least be hinted at.
For the Ruger, sized-and-sorted Champion ammo seems to string itself out in a roughly horizontal group. I suspect it may have some relationship to something mechanical going on inside the rifle. I suspect a bolt action rifle like the CZ will work best with anything that is as consistent as possible. We'll see.
And I ordered a brick of Federal Champion Match, which I will test against my home-rolled ammo. Since I've run across four different rim dimensions in the stock ammo, I suspect they have four different machines to make the cases. They may use only brass from their "best" machine, and test more regularly for consistency in the match ammo.
As with science, each answer brings up two newer-but-subtler questions. But with a dependable standard rifle and ammo combination, these new questions should be quicker and easier to answer.
I can't speak for anyone else, but I find when I build, modify, tweak, or study something, my subconscious more readily accepts that device as an extension of myself, and I have a more instinctual feel for how to use it, with a lot less work on my part.