Recently picked up a 16 bore SXS barlock hammer gun.

It has the following on the top rib - A.B.PER.K.PETERSONS EFFERTER IMP.
No other ID markings, no marks on lock plates.
The gun has Belgian BP proof marks.
So probably sold by a dealer in Scandinavia somewhere.

Anyone shed some light on the PETERSONS??
on EFFERTER IMP??
Thanks in advance
EP