My older rimfire prone gun used to love Wolf Match Target. I know a lot of folks don't ascribe to sorting ammo by rim thickness. I agree that doing so doesn't improve group size, it don't make the ammo more accurate. But what i have seen is, that by sorting by rim thickness, it removes the "fliers". So now, you have ammo that will shoot the same size groups so much, but in tangents on the target in relationship to the original POA. So a certain rim thickness lets say, prints on the target at 1 o'clock, but it does so consistently. Center up, the next rim thickness moves that to say 8 o'clock.. get what i am saying.. With better ammo being used, those deviations become smaller, oh i think that they are still there, just not to the point that it will be helped by sorting by rim thickness.
i also agree that, Federal Auto Match isn't "match grade" ammo, but there are rifles out there that just love the stuff.. i have a Rem 37 that seems to want to shoot bugholes with it.. i don't have a gauge to measure the rims, i have shot some "fliers" with it, but i think that it was due to the blustery windy does i have been to the range with it.. i have not had it long. I can tell you this.. it don't like SK Standard Plus!