I don't know what it is, but I like all of these 9.3's. My CZ550 really won me over after using it on that cow elk 2 years ago. It's accuracy is also second to none. It seems the cartridge itself is very inherently accurate and is the reason I've been thinking about re-boring one of my model 70's to the 9.3x62. Personally, I think I could chit can everything else and just hunt the world with a 9.3x62....