Out of curiosity I made a few assumptions and then put them into my ballistic roundball program to see what it would say about the drop of a heavy Minie' ball.
Based on your load and powder, I'm guessing your guns muzzle velocity was about 1100 fps.
Then, I guessed your Minie' weighed about 530 grains.
Setting the range at 25 yards, and using the 1100 fps and 530 grains for the slug, I told the computer to do its thing.
It said the drop at 25 yards is zero which is of course reasonable because I told it to zero it there.
It went on to say, at 50 yards the Minie' would drop about 1 1/8 inches. At 80 yards the drop was 5.3 (5 5/16") and at 100 yards the drop was 10.2 (10 3/16").
Just to see what it would say for a .58 caliber roundball (282 grains) and 1100 fps velocity I poked those numbers in with the aim point set at 25 yards.
It said the drop of the roundball would be 1.3 (1 5/16") at 50 yards, 6.4 (6 7/16") at 80 yards and 12.4 (12 7/16") at 100 yards.
At 100 yards the 1100 fps muzzle velocity had fallen to 939 fps for the heavy Minie' while the velocity of the roundball at 100 yards had fallen to 841 fps.
Now, these answers aren't real accurate because the computer program assumes the nose of the Minie' is a sphere and because the nose of the Minie' is more aerodynamic, the velocity won't fall as fast but, I thought it was kind of interesting anyway.