I have several very accurate target rimfires. To make them work, I have tried at least 6 types of top grade target ammo. My 40X Remington likes a particualr lot of Eley Black Match [$1100.00/case] My Suhl 150 likes another lot of the same, but has a tuner, so shoots several top ammos very well indeed. My 541S is a Lapua Center-X user, while my 541T likes RWS R-50 of a certain lot. I have a case of Lapua Super club and a case of RWS Rifle match that are great for general purpose work and silhouette, but I would not take them to a 100 meter benchrest match. I still have a bit of Lapua Midas M & L., some Eley Tenex [Red Box] Certain rifles work well with these as well. You just need to try several ammos and lot numbers to sort them out. As has been noted, if you find a lot # your rifles dotes on, buy lots! Just a point of interest: HV ammo is generally regarded as not worth shooting at competition, but I have a bit left of a lot number of unplated HV stuff that I have won 100 meter bench matches with a couple of times in my 541T. Regards, Eagleye.