My guess is that it was originally a 9,3x57R (360 2-1/4") that was so popular in Sweden and someone had a pre-made liner set up to fit in a .410 barrel. It would have been easy to ream a bad (or no ammo available...) 9,3 barrel to .410 and then with no other effort have a lined .22 something.

Hand waving and hocus-pocus, I know, but it does make a bit of sense.