I was going to do the same exact thing. Never got around to it. I was gonna throw Pyrodex Select RS into the mix also.
I bought the Schuetzen, Goex, and Swiss with that intent, all 2F.
Did not buy any Old Eynsford.
I am extremely interested in what you find out, if there’s much of a difference between the powders.
Amount of fouling left in the barrel was something else I was wondering about. I always thought black powder was so much dirtier than Pyro and 777. It really cleans up just as fast as either. I think the fouling of real black is a touch darker than 777, about the same as Pyro, and it doesn’t seem to leave any more crud behind. It’s just darker. Dirt has many colors.
What got me wanting to do that was last year I did an accuracy test with Pyro Select RS against Pyro P and Black MZ. Exact weighted charge, I mean EXACT weighted, 3 shot groups, based off of 80 gns volume.
I didn’t check velocity, but accuracy was not even close. Pyro Select and Pyro P clobbered Black MZ. There wasn’t enough difference to declare a winner of the Pyro’s. This was before I had real black powder. I actually bought it after watching you shoot with Swiss and out of curiosity in the accuracy between all of them.
I wish I had more time.....
Here’s the test I did if anyone is interested. I tried my best to be consistent, and I realize one round of testing doesn’t prove a lot but, the shots all felt good and I’m betting if I did it again, I’d get similar results. I’m also thinking it would be hard for me to get any grouping better than I got at 100 yards. I was shooting from a lead sled and my crosshairs were still “hovering” ever so slightly.