Have been in contact with a couple different guys.
The general consensus is that the Shotgun started out as a Civvie Husqvarna Model 12, and was likely restocked at some point. There is evidence of a couple spots being filled in, on the underside of the barrel, that would make me think it may have been a full-stocked gun at some point. As far as I understand things, the bayone lug would be on the side of the barrel, rather than underneath, so the small square with traces of brazing around it, could have been the remains of the forward lug for pinning the full stock in place,or... ?
Apparently the "N" marked breech blocks came on the scene about 1932.
The overall condition of the metalwork makes me think that the breech block may be newer than the rest of it, but the makers were not as keen to mark the birthdate on the receivers, as were the military contract guns marked. I have been over the barrel carefully, and cannot find any markings other than the alignment notch in the center of the bottom flat, matching the one below the receiver ring on the front face of the action.
The inside of the barrel is in far better shape than I would have expected to find, given the state of decay on the outside. I have my suspicions that the barrel may have started life as a military rifle barrel that was bored out to shotgun size. The bore is considerably off center at the muzzle end.
There also seems to be a crack in the barrel at the breech end. I think this was the reason it was welded shut, as it would definately have been unsafe to continue shooting it.
The safety hammer was introduced in 1902, but there is no telling whether it was used on all the models produced from that point onwards, or if it was an optional extra.
From what I can gather, the Model 12 was in production until the late 1940's. I suppose the makers were on to a good thing, and there are few parts to go wrong, so it would have made sense to make them as long as they would sell.
I too am interested in seeing what there is to say about the pitfalls of the 8mm actions, as I was looking at a couple of them as possibles.
Gonna have to get my head around the fillers to use, as well as the appropriate prep to weld the groove full, that was filed into the top of the receiver, to be used, I suspect, as a rear sight for the shotgun. Too bad the breech block prevents it being seen when closed.
Cheers
Trev