If you have access to Wildcat Cartridges Vol. II from Wolfe publishing, check the data for the .224 Clark. Dimension drawings show it is a little longer to the neck/shoulder junction (11.933") and a little fatter at the shoulder (.455) than Hornady's drawings for the standard .22/6mm; it has a 30 degree shoulder. I don't know the dimensions for the .22/6mm AI, but I'd suspect they are close enough for starting loads.
