I shoot the same 629 6.5" 44mag. In my speer manual, 17.7 gr 2400 will give you 1271 fps. This is the max load.

I shoot 23.5 gr Win 296 with 240 gr xtpbullets but I will be switching to Cast Performance lead bullets since the lead now used is an alloy an it much harder than the old SWC bullets.

H110 and Win 296 are pretty much the recognized powders for hunting loads for the 44mag.