My Uberti-made Remington .44 Army will take a 40 gr. measure of Goex FFFG powder.
However, that's deceiving. Curious, I recently weighed 10 charges from each of my flask spouts. My 40 gr. spout actually threw an average of 37.5 grains, as I recall (I'm at work and can't look at it right now).
All of my spouts
The point is, what the spout shows isn't always the truth.
By the way, the above is without a greased wad, just the naked ball.
I use a loading stand, which holds the revolver upright while seating. Not only does it give you a better feel for how much force you're applying, it can help you seat a ball below flush, over a large charge.
REMINDER: Hodgdon 777 cannot be used as a substitute with black powder, volume-for-volume. Hodgdon lists 35 grains as the MAXIMUM load in a .44 cap and ball pistol, though the chamber will surely hold more.
If you use Hodgdon 777, reduce the load 15 percent (by weight) from what you normally use as a black powder load.
Hodgdon 777 is good stuff, but it's powerful. It's also expensive. If you can find it easily, you're better off with regular black powder.