RB's from the 12 bore run to 1,550fps with black powder, sometimes just over 1,600fps with smokeless powder. Black Powder to 7 drams (191gr.), smokeless, use SR4756 or SR7625 and start around 25gr. and work from there. I've not used Blue Dot in the 12 bore, but have used the SR's as well as herco, which is just a bit slower than Unique.

One could start with H4227 or IMR4227 at around 50gr. with RB's in a nitro-proofed gun. Wads or wadding is needed to fill the space required to obtain a proper crimp, roll or folded. I use a folded crimp with smokeless loads, normally.

Normal Parodox Gun velocities I've seen in print usually run below 1,100fps for regulation. This, presumably due to the light weight of Paradox guns and heavy bullets. Heavy bullets at low speeds cause incredibly high trajectories which cause misses and wounded game. Any range past point blank becomes very difficult. At 1,100fps, with a 10" or more trajectory over 100 yards, the heavy slugs have no real point blank range. Round balls weigh less and if can be made to regulate, will give a better account of the gun on large game. The 7 dram charge mentioned above, will give a point blank range of 110yards, where the ball is no more than 1-1/2" above nor below the line of sight. Put in a 2" number, and zero for 90yards, and that PB range extends to about 125yards.