1937 Mauser

[DonVoigt]

"Mauser initially remedied the problem by lengthening just the upper part of the frame by 1 mm. Since they were using half finished DWM frames this caused the hump seen on some early K-dates. Thus, they reinforced the DWM frames and caused the hump appearance.

Then as they started using their own forged frames, they just machined the entire frame at 130mm, thus thickening the frame, hence re-inforced as compared to the DWM frame. But the hump disappeared. This continued until early 1937."

Guns3545,
Are you sure about this? Any documentation?
What I've read is that "finished" frames went from BKIW to Mauser.

How would they have added to the frame to reinforce a DWM frame? If the frame was long enough to mill with a hump, why not just leave it long?

IMO,
Mauser developed the longer frame in response to a complaint/problem and only in their own mfg.; it doesn't make sense that Mauser would "waste" time on salvaging frames when they could have simply used them as is.

Just a matter of semantics, but should not the frame be described as lengthened and not thickened? Usage in the above explanations and discussions slips back and forth between the two and could be confusing. At least to a dummy like me.