FWIW, the only "quick and painless" sight regulation I've ever done on a repro 1860 happened when I brought the wrong sized balls and flask spout by mistake and had to resort to using only the small supply of Pryodex pellets and Buffalo conicals I had taken along as an afterthought or go home.
In my then-new 5 1/2" Pietta 1860, I was astounded to find that not only did that combo shoot exactly where I aimed out to 25 yds, but would plunk them into nice, round 2 -3 " groups, too. Every single other C&B revolver I've ever had took at least some amount (in many cases, a great deal) of tedious experimentation with various powder charges and repeated cut-and-try sight alterations to get even close to that result.
Personally, I'd start out as mykeal suggested and move in closer at first. Working systematically from a solid rest and using a calibrated measure or dippers to throw your charges, find the one which gives you your tightest average groups regardless of where they're printing. Then either find a flask spout which delivers that same volume or alter an oversized one to do it.
Then comes the tricky part: altering the sighting notch in your hammer to regulate your POI with your POA.
DON'T GET IN A HURRY! IMHO, it's best to do this with a couple of high-quality needle files rather than grabbing your Dremel and a cutting wheel, even though that case-hardening can be a b***h to work on at first. It's only a very few 1000ths deep, and power tools can wind up taking off more metal than you want or need to REAL fast if you get impatient or heavy-handed with them.
IIWY, I'd start by getting your groups centered for windage. Rear sight= remove metal on the side you want the group to move towards. Take just a very few file strokes off at a time, then carefully firing at least one group after each alteration. This can take several tries to accomplish but you can buy a considerable amount of powder and lead for the cost of buying and fitting a new hammer, so BE PATIENT.
Once that's been done, move back to the range you plan on doing the bulk of your shooting from and regulate for elevation. Generally, this will require making the notch deeper to bring the groups down. Same system as above, please.
A somewhat more expensive, if less labor-intensive, alternative would be to have a 'smith cut a dovetail in your barrel and install a "tall" blade-type front sight. Then you just need to "drift" it slightly in the dovetail for windage and file it down for elevation. Not "Period Authentic", but it does work just dandy.
Hope this is of some help.
I measured the colt spout and it only held 25 grains. Now I am no marksman but I think I can shoot something that big from that distance. Was the powder charge too small? And I have found just by plinking around that by not using wads gives better performance. OK ---I think I should use 30 grains in that gun w/out wads or am I just a bad shot w/25g/w/wad