After re reading the OP, and all the other great posts, it seems the question could be simplified to,
Is it possible to compare the accuracy of two accurate rimfire rifles that are both able to shoot better then the ammo available for testing?
I should have seen where this thread was going after reading all the Tuner threads.....![]()
It's certainly possible to compare two rifles shooting from the same batches of ammo and draw conclusions.
It's also possible that since we can't vary powder charges to tune ammo as we do with centrefire, and not everyone has a tuner on their rimfire, the main variable we can change is the type of ammo, and it's very possible for a particular variety to land in the sweet spot for one rifle and the wrong spot for another. Don't be surprised if one rifle is better with one kind of ammo and the other does better with another and you can't get a clear "this rifle is absolutely better" result. And with any semis in the comparison, what cycles cleanly will be an issue too.
Earlier I made the point that skill is a big part of it too; a total newbie is going to scattergun the backstop regardless of their gear, and getting past that stage of one's shooting career is the biggest single improvement that can be made. But a lot of us are up to a level of competence where we can see differences between guns and between ammo varieties, and those differences are even sharper in the hands of the wizards. Also, benchresting makes it a lot easier to compare and wants more technical skills, while freehand shooting is a much harder physical skill.