Most accurate rimfire ammo I know of since the mid 1980's came out of Russia after the Iron Curtain fell. A friend finally got permission from the US government in the early 1990's to import rimfire ammo from the plant in Klimsok, Russia, where the ammo came from that the former Soviet Bloc used to win so many international matches and set a bunch of world records, too. Olimp was their top brand and Temp was a close second, Junior Brass was a popular brand for plinking stuff.
On his first visit to their ammo plant, he brought his smallbore match rifle and they made a few short runs of ammo with different charge weights. Testing those lots at 100 meters, a couple would shoot about 3/8ths inch 10-shot groups. A bunch of that ammo finally got into the hands of top USA smallbore competitors and they did well with it.
But alas, the Russian mafia took over the plant and shut down the rimfire production lines a few years ago. The only stuff they make now is food for AK-47's.
On his first visit to their ammo plant, he brought his smallbore match rifle and they made a few short runs of ammo with different charge weights. Testing those lots at 100 meters, a couple would shoot about 3/8ths inch 10-shot groups. A bunch of that ammo finally got into the hands of top USA smallbore competitors and they did well with it.
But alas, the Russian mafia took over the plant and shut down the rimfire production lines a few years ago. The only stuff they make now is food for AK-47's.