Raimey,
I can't get a very clear of the gun either, but I see the "bands" you mentioned. They are in the same location and have the same look as those used to hide the barrel joint in a monobloc gun, as you wondered. The barrel set on a German rifle of this age and action type would normally be expected to have been joined by "bundling". If the gun were re-barreled to correct badly corroded barrels or for preference, the work would be done by "sleeving". In this case, the same type bands would be used to hide the joint. A "hands-on" inspection or much better photos, or both will be necessary to determine what happened. If the gun was re-barreled, the original barrel proof marks would likely have gone with the old barrels and new proofs would be applied to the new. In the absence of good info, this is only conjecture.
Mike
