The Pedersoli's still have 2 sights - supposed to sight each one for a separate barrel. Lift up the appropriate sight.
Here is my .58 Kodiak.

I was able to work up a load that got the barrels shooting together using round balls and 2F GOEX powder.
I don't have a target, but 110gr. of 2F actually made the barrels shoot parallel. Just luck.
Most of these guns are used with slugs of one sort or another. The result us usually measured close to or
just over a foot difference at 50yards, with both elevation and windage problems.

After I found these two loads, I was able to remove one sight. I filed out the remaining sight to a wide V and used
the gun to good advantage on our trail walk, acing the trail a couple times. I really enjoyed smacking the 100
yard plates with a fast right and left.