I have shot and built a few BP firearms. As to pyrodex, I have heard too many people badmouth it for its corrosion no to take them seriously. Most claim that they clean and find serious rust afterwards. Another powder worth a try is the Swiss black powder if you can get it. It seems to run about $20 or so a pound, but is used a great deal in BPC competition as it burns moister. It has also been recommended for use with regular or even pistol primers as compared to GOEX with magnum primers in cartridge. Muzzleloading shooters like it also and claim it gives the same performance at about 10-15% less powder charge. Goex now makes an Express powder to compete with the Swiss. Goex itself has been a standby for years when nothing else was available and is not all bad. The real thing is what shooting a muzzel loader is all about. Another cure for low fences is to buy the brass flash cups available from suppliers like Track of the Wolf. I ahve used them on drum and nipple firearms and see no reason they would not work on patent breeches as they also protect the metal around the flash. They are very inexpensive.