I have one of those Husky's, but the left barrel is rifled- straight. It is .705" groove to groove, so a tight 13 bore, while it is chambered for the 16 bore brass case.
The serial # puts it made around 1900. Husky data shows the smooth bore, a 16 bore, is meant for paper cases with shot from it's modified choke, while the rifled barrel is meant for a brass case with round ball and black powder load.

It shoots to the sights with 3 drams of 2f BP, filler wads and a patched .662" or naked .684" naked ball. The cloth patched balls are more accurate from the straight rifling and due to the lubricated patch, there is no fouling buildup shot to shot.