I just picked up the 2021 Hodgdon reloading manual. The new Wincheser StaBALL 6.5 powder appears to be VERY impressive in a lot of different cartridges including .22-250. In the 50-55 grain bullets they were getting over 3800 fps. That powder also offers copper eraser and unlike just about any other ball powder is temperature stable. I'm not sure how easy it is to find but I intend to try it as soon as possible.
