First of all, some links to a few pictures of my Ruger Old Army nitro conversion revolver which allows me to load the gun with the cylinder in place rather than having to remove it to load using a small press which is normally the case on UK conversions or purpose made muzzle loading nitro revolvers.
https://i.imgur.com/33xXWRNl.jpg
https://i.imgur.com/p5SEooyl.jpg
https://i.imgur.com/8L92G2el.jpg
https://i.imgur.com/p5SEooyl.jpg
I tried increasing the load in small increments from 5 to 6 grns of Herco at the range today. The heavier loads grouped higher, but still suffered from the presence of some unburnt powder with the occasional light discharge. A definite improvement this time though as the 5 grn load grouped into 4" at 25yds unsupported with the fewest light discharges. I will now try a faster powder and some .460 ball to see if things can be further improved.
Regards
Brian