I own one of the 20/20 smoothbore pedersoli howdah pistols, got it in kit from at Dixie.

It's truly a ripper with tightly patched .600 roundball on 70gr FFg Goex.
With this load it prints them right next to each other, right over the bead at 35 yards.

That powder load is essentially the same load I'd been running in one of the 16-bore rifles - had the old powder measure (dipper) from a cased set on the bench that day and 'filled her up' with Goex.
The sound is glorious.
The recoil is about what you'd expect, and the pistol handles very nicely.

The .58/.58 (with a 1/24" rate of twist, by the way) appears to be a new offering in the pedersoli line and I might have considered it when I got mine (couple or so years ago) but in retrospect I'm glad I got what I got as it's very consistent with the big powder charge, and it runs nicely as a shot-pistol with less powder and #5 shot.

In field terms, especially where it'd be practical - 35 yards is about the max distance you'd expect to encounter something needing a gunshot in the woods.
The 20/20 does it - and it's versatile.

Cheers
Tinker