It has been stated many times the AI version of the 22-250 case is near equal to the swift case. That being said it has also been stated many times that the factory 22-250 case is 95% of the swift capacity. So wherein does a mere 5% increase in 22-250 case capacity bring about a change in burn rate to create an ideal powder? If it was a necked down .243Improved or 6mm Rem-.22 improved then a considerably slower burning powder could be justified.
As to H414, I have used a load straight from the Speer #10 manual for nearly 20 years in a Ruger #1-V 22-250 with no problems and I get 3,800+ fps.with a 55 gr. bullet. The standard case is quite capable of handling H414.
If pressure tested data from reputable manuals is compared, both the .220 swift and the .22-250 use essentially the same propellants only the Swift gets a somewhat larger charge to achieve it's increased velocity.