Somewhere on this website is another thread on this very same topic. Search it out. I've only tried them in the .300 MiniWhisper cartridge, which is an oddball wildcat based on the .30 Mauser pistol case. My experience was terrible. They were very inaccuracte and I even got a lot of "keyholes", that is, bullets going sideways into the target. But it's a fun experimental handloading project. Just think "safety" until you get a load that you like.