Smooth barrel?..Yes.

..and again, 3 indentsments are roll die unto the barrel. They go all the way out and they have a twist of something like 1:70 + they sqeezes tighter towards the muzzle.
Here a .743" roundball are situated aprox 2" in the right barrel after the chamber.

Invisible rifling is "invisible for sure. It took me a long time to realize this.
A 735" paradox bullet just barely touches the barrelwalls and the "rifling" has no way to steer it.I have shot a new H&H paradox ammo in it and they just fly sideways.
I have concluded a larger paradox bullet of something like .745" is needed for this gun.