"It's clear that the toolings built by DWM and by the Erfurt arsenal were different, utilizing different milling techniques."
"The Erfurt Equipment that went to Simson used the same milling technique. I expect that Krieghoff frames would show the same."
Actually it looks like the difference is not in the tooling, but in the order in which the final milling strokes were made. DWM practice appears to have been to finish the sides and back inside the frame first, then to make the final center routing stroke.
Erfurt practice seems to have been to make the center routing first, then finish the sides and back, intersecting the upper arc of the center stroke. Considering the origin of the Simson tooling, the similarity of machining makes sense--one can imagine the instructions for use coming along with the tools.
Actually, the rear frame Krieghoff finishing follows the pattern of DWM.
Here is a picture of my Dutch Vickers frame for your study.
As was mentioned, Vickers was supplied with sufficient tooling to finish work the parts. The most logical conclusion is that the inner frame machining characteristics represent Vickers finish craftsmanship.
The deletion of the two vertical 'inner ears' makes sense. They are completely pointless anyway 
I'm not so sure they are pointless. They provide the only critical lateral positioning guides for the rear toggle piece--rather than depending on the manufacturing tolerances of the inside of the frame ears
plus the manufacturing tolerances of the receiver extension widths.
--Dwight