Some time back, I traded into a Kodiak .58 SxS Pedersoli rifle. These come with 2 adjustable sights, mounted on the rib in the middle of the barrel. Since the leaf folds down, you are supposed to sight each leaf in for one of the barrels, raising and lowering the leafs as needed.
As received, the hammers did not curl over the fences, actually sitting proud on to of very high nipples, allowing cap fragments to fly all over - no protection.
here is the 'action' as received.

I did not like the relationship of the nipples, nor the bright steel of the locks, tank and trigger guard, nor the horrid cheek piece, so I changed those items and refinished the stock. I also filed the rear sight to a V shape. so

I started off using 3 drams(82gr.) of 2F GOEX powder with a .562" ball and .021" ticking patch.
The barrels printed right barrel 2" over the left, and 2" crossing using just one of the rear sights. I increased the charge to 90gr. and the barrels came closer together, using the same combination of components. I increased the powder further and the barrels then shot one above the other about a couple inches apart at 50meters+. This is displayed on the left target. The right target shows an offhand shot, one from each barrel holding accordingly, right barrel low and left barrel right on, still using just one sight. by this time, I had removed the front, rear sight from the rib.

After this test, I changed to a denim patch of .022" thickness - note the change in grouping!

I increased the charge further to 110gr. and found the barrels shooting almost exactly parallel with that load and the .562" ball. I changed to a Lyman mould casting a .574" ball and grouping remained the same- parallel with 110gr. and into the same group with the .574" and 100gr. 2F. As grouping at 100 meters was the same from the 100gr. load and the 110gr. load, I stayed with the 100gr. 2F charge. At this point, I used this rifle for trail walks at our club and relished in shooting rights and lefts on the gong targets- clang/clang. Oft times I'd run the whole course with narry a miss. I then became bored with this rifle and sold it to a lawyer in town. I'd actually like it back now. Hmmm.