[10 Spot Terminator]

It has to do with the bullets construction and its capabilities not published load data for any particular .22 calibre cartridge. There are bullets made for varmit hunting that have different jacket construction and again different velocities fall within the capabilities of those bullets as well. The twist rate reference takes this into consideration as well as to present the best optimum performance to avoid what is known as over stabilization of the bullet which can create some foul flying bullets if the twist rate is too fast up to and including key holing or jacket seperation in the worst cases.