Generally, with handguns, reducing the velocity or increasing the bullet weight will raise point of impact at short ranges.
Every gun is a law unto itself, however, so it doesn't hurt a thing to try.
What I KNOW will work is to file a "cap" for your front sight out of a piece of brass, and either pin or epoxy it to the top of your existing sight, then file it back down to get POI and POA together. If you fit it closely so that it sits down snugly on the existing sight, this should be a one-time deal.
The other approach is to dovetail a front sight into the barrel.
I have generally had better luck w/ percussion revolvers with a full charge of 2F BP and a lubed wad under the ball versus 3f, even in reduced charges. If you play with filler, you could very well find a load that shoots as accurately, but fillers are a pain in the neck with a gun that is already slow to load. In addition, 2F seems to be kinder to the open-top designs and was what they were usually loaded with in the "old days".
The important thing with the lubed wads is make sure they seat down on the powder far enough so they do not touch the ball when it is dropped into the chamber mouth. The ball will self-center if nothing is touching it.