I shoot a load of 9 grains of Red Dot in my 444 with a 275 grain gas checked bullet and it shoots very well. Plenty of data available for the 444 with 240 to 250 grain cast. I"ll agree that when the velocity rises so does the recoil. For this reason the heavier 444 rifle will be softer recoil than a comparable load in the lighter 44 magnum. 44 magnum load data would be a good place to start for 44 magnum equivalent loads in the 444.
Good luck!
Rick