Hobie, I used Pyrodex in my cap and ball for years. Then I decided to hunt deer with it. I sighted it in and went hunting. I shot under a deer 3 times at the same distance I sighted for which was 25 yds. I went down to my range and shot at my steel plate and all 6 shots hit the dirt under it. I went back a few days later without adjusting the sights and was hitting dead center again. Same can of powder.
I switched to Swiss FFFG and the problem went away and I picked up a lot of velocity. I dropped a deer with it this season. Accuracy is way better too. Anyone want to buy some pyrodex---CHEAP.