So I shot it.

It takes 75 to 80gr of fff to cover the top of the pillar (thank you Daryl).

With that load it is potent to say the least but I noticed a few things.

Apparently it handles round ball well, shooting slightly high at 50ft with the low rear sight.

Strangely it also shoots to the left by around 1.5" consistently.

Would the inertia and drag of a conical cause it to shoot to the right? The sights are fixed so I can't imagine the point of impact changing in the last 180 years.

Also, if you look at the pics, the rear sight has two positions. If this thing is shooting high at 25 yards, the high position on the rear sight is nearly .300 greater on the 11" sight radius. That adds up to a 17" correction at that range.
What could that sight setting possibly be for?

Curious as to your thoughts.

Tom