We have a member here (grenardier, I believe...) who owns and shoots a modern production H&H Paradox.

I'm sure he could comment on the effectiveness of the design based on modern production and modern ammunition.

Gatsby - how many different Paradox guns have you owned and shot?
We have other members who also own/ed Paradox, Explora, Ubique, and others from other makers.

Also see Hamilton Bowen's work with special ball/shot revolvers.
A common theme with the long guns and Ham Bowen's revolvers seems to be relatively abrupt and severe choke rifling. Bowen uses Colt brass and bullets through backbored .44mag barrels.
Someone here can share the bore and constriction numbers from their ball/shot guns.
Successful bullet designs all seem to have one deep and wide grease groove and they tend to be cast of relatively soft alloy - both for the long guns and for the Bowen revolvers.

Cheers
Tinker