An update. After putting the ol gal on face and replacing a firing pin spring on one chamber, it was off to the range. Using my previously described light loads, I proceeded to test fire the shotgun. I am well pleased to say the least. It is an interesting set of chokes -- one Improved cylinder, and the other, full. But it shoots great, points naturally and patterns well where aimed. It may be a "clunker", but for what I'll be using it for, it will serve as well as any Parker and is a pretty thing as well.
I would still appreciate any thoughts and information on the Max Neumann theory of origin that I previously posted on this thread. Thanks for the help.