I got the fantods (Jack O'Connor) from too many hours of building another close copy of the Kit Carson Hawken. It was 50 degrees here and with no snow, I figured I should take a break and try out my .58 Leman, recently rebored by Bobby Hoyt from a .54 GRRW barrel that went through a fire and had been rebuilt by me into an elk rifle. I made it as a caplock then changed it to a flintlock. It has a 24 inch 1 1/16" barrel, which was too pitted to lap smooth. Thus the rebore. I hunted elk with it one season two years ago.
(I typed the text then uploaded the pictures and don't know how to move them where I want them. Sorry about that).
Today I tested five powders in it, using .570 cast balls and .016 linen that crushed to .010. I made weight calibrated measures for each powder. Shot four-shot groups of each at 50 yards through my Oehler 35P chronograph after a first fouling shot. I had a damp cleaning patch on the seater jag, thus wiped the bore at each loading, but did not clean between powders until after the fourth one. The 100 grains of Goex 2F grouped well and the patches were good. Then I went to Olde Eynsford 2F and 1 1/2F and the patches blew. So with the next powders, I used .019/.012 Levi, which held together so well it could have been used again, but required hammering the short starter to get the ball in the bore. I need a thinner patch.
With no cleaning, I went to Alliant Black MZ. This is probably to be loaded volume equivalent to Goex 2F. I weighed those charges, and they averaged 88 grains, this being a coarse powder. But to test weight equivalent charges, I made a measure that held 100 grains of BMZ. This will not ignite reliably without a black powder booster charge, so I poured the measure full, then tapped out 5 or 10 grains and filled that with Goex 2F and poured it down the bore. Real black powder must be used in the pan, I use about four grains of Goex 4F. This results in perfectly reliable firing, I would trust it in any situation.
I had not cleaned the bore before this test and the velocity spread was large, but the group was good. I then cleaned the bore to go home, but decided to shoot the Swiss 1 1/2F with good patches. Then I had all the testing I wanted.
I have also used Black MZ in a .45 flintlock Lancaster style rifle I built, and it worked perfectly, with the black powder boost and black in the pan. Anyone who says Black MZ or the Pyrodex or Triple 7 powders will not work in a flintlock has not tested these powders adequately to state that as fact.