I acquired this Ortgies rig recently. The pistol's slide is stamped with an entwined script "BS" on the slide. I've owned a Kar98a with the same mark on the receiver and stock and encountered a pawn shop Luger and an online auction bayonet with it as well. Other people report seeing it on Gew98's. The meaning of the marking is unknown. Some have held that it stood for the Bahnschutz but specialists in German Police markings dispute that. Until someone uncovers some heretofore unknown information the marking's significance is lost to history. The pistol itself is a late production piece in very nice shape and came with an extra mag and a well worn holster whose only marking is an eroded fat wing eagle/swaz. The seller told me that the rig came with a "capture" paper but he had forgotten it at home. He promised to mail it to me ASAP. Well ASAP turned out to be almost two weeks but it arrived today.
Here are some pics.