Had a couple of my 22 rimfires out last night testing some unplated run-of-the-mill ammo. I shot CCI Blazer, Fed Hi Velocity, PMC Scoremaster, and WW Wildcat. My 541S absolutely detested the PMC offering, shooting only about ¾" at 50 Meters. However, the 581 digested it just fine, actually outshooting the 541 with it, averaging .55" The blazer shot an average of .33" at 50 from the 541S [5-5 shot groups], the 581 averaged .44" The Fed HV stuff shot an average of .61" from the 541S, and .77" from the 581. [Always a flyer in the group, sometimes 2] The wildcat shot well in the 541S [.41" avg], but the 581 did not do well with it [.89" avg] For comparison purposes, these two rifles will shoot match ammo they like ito pretty impressive groups, the 541S will average .18 @ 50 with Winchester supreme Match or Lapua Club. The 581 likes Green Tag and will average .35" @ 50 with it. Even one lot of Winchester T22 I use gives .38" avg. I will be testing more ammo as I have time and will report. FWIW, I ran some of the Scoremaster across the chrony also, averaged 1144, but too much variation to qualify for a match ammo. Regards, Eagleye.