23 to 24 grains H110?296 seems to be the sweet spot for 240gr XTP.
I use 23 as I use the same load in all .44s so I don't have to worry about pressure issues. I get 1400 FPS from 7.5 in Redhawk which is my benchmark/workhorse. This load will give one hole with a scoped Redhawk @ 50 yds I tested for a friend. I still use irons

I can only get 19 grains in 44 case with 300 grain Swift. Any more and the case crushes when you seat the bullet to the cannelure.
20 grains in case with 300 gr. XTP gave 1200 FPS with SD of 7.
This load gave one ragged hole out of FA 83 6in @ 25yds off bench
with irons