They did say it was based off a .27 cal nail gun cartridge. Substantially fatter than the .17hrm and .22M.
IF their illustration is to scale AND my skills with a caliper can be trusted, there is approximately 0.009" differences in head diameter. 0.286" for the HMR (wikipedia) extrapolates to 0.295" for the new WSM. Approximately a 3% increase.
I bet Ruger will have little difficulty adapting it for their 77/22 .... Little work to their Hornet magazine and boom
