Unique is probably the powder that's the most appropriate for the most calibers in use today as it was yesterday.
I think that Unique and .44 Magnum are a most beautiful couple and go very well in the same combo;anything between 7 and 10 grains depending if you want ''bing'' or ''medium boom''will give you satisfactory velocity and accuracy.If not,I'd first look at the quality or mechanical integrity of the gun.