My experience is these guns cross low when the velocity is too low. I suggest you get a copy (if you do not have) of the DGJ issue where Sherman Bell discusses loading for Paradox guns. If you follow his methodology, you will be using Unique, shortened Federal Paper cases, nitro cards and cork wads. You may roll or "fix", John Millar in Canada can make you the proper roll crimper for the Fosbery slugs. As I read through this thread, most of these have been recommended by others. Sherman's loads will almost surely be safe in your Ball & Shot, so this is a really good place to start. I believe 19 grains of Unique was a starting load that worked in some of the older black powder guns? Also, if you used the 19 grain Unique load in Magtech Brass shells, instead of Federal Paper hulls, you did not follow the suggestion at all...

There are so many variables in creating ammunition that will regulate in you Lancaster that it is almost a waste to not chronograph each and every combination. Almost surely, your projectile should be traveling between 1050 and 1150 fps. In a few cases it should be about 1200, but there are usually clues to the faster load, like a B&S that weighs 7.5 lbs or more.

BTW, I worked up loads for a late Wm. Evans, you can follow my reporting on older threads on NE. The range had a large pond next to it. More that once I fantasized about hurling the paradox way out in the middle of the lake. These things can be frustrating.

Sounds like you have a B&S that will eventually produce 4"-6" groups at 100 yards. Good Luck.