If it's on the front of the receiver, it likely is a B. In the late 20's and 30's the front of the receiver did have the model stamped - or an 8 on a 99R for some reason. Not sure anybody has ever reported what was on a 99B, but apparently it's a B.
I think the earliest Spiegel we have is 359,xxx. I don't think this is likely to be a Spiegel being that it's from 6 years earlier. What it is probably remains to be discovered.. another retail outlet deal? A gun shipped to whoever made the bases for these? An after market mod?
Things like this are what help us keep digging.
