I forgot to put for the 44magnum.
heh, heh, I thought at first you were talkin' for your .460. I was gonna say you're about 25 grains short.
Hornady's manual lists 17.5 to 20.1 of H110 under their 300 grain XTP.
Hodgdon's website recipe is 18.0 to 19.0.
Hardly ever see Hornady hotter than Hodgdon.
IMHO, it's your call, but I wouldn't start @ 19.5. I would start @ 18 and go from there. Handgun or rifle?