Thor/CV,
* Randall Gibson, in
Krieghoff Parabellum-Pgs.27 & 28 examines the frame hardness of various Luger Mfgs. in an attempt to see if the origin of the frames could be determined by the relative degree of hardness. Using a Wilson Rockwell hardness tester, against a B scale standard, he recorded values for a 1917 Erfurt (B-21), 1917 DWM(B-22), 1918 Spandau(B-21), 1924 Bern(B-10), a Vickers(B-22), 1925 Simson(B-33), "S" code Simson(B-33), 1937 Mauser Banner(B-31), byf'42-KU(B-31), 1937 Krieghoff(B-32), & 1945 Krieghoff(B-31). Conclusion, the frame Mfg. could not be determined solely by the hardness value.
* A correlary from this data is Simson & WWII mfgd. frames were harder than Swiss & WWI Mfgd. frames.
* Conventional wisdom holds the development in ore refinement, better alloying, improved equipment, and tighter heat treating process control all became markedly improved as the 20th Century progressed. This wisdom nicely summarized by the Burmeister quote above.
* Mauser M98k rifle actions are extolled for their soft core to absorb cartridge impulse shock while hardened on the exterior(skin) to withstand rough mechanical handling treatment. Those who have drilled/tapped for a scope mount can attest to the 98k surface hardness.
* Does the "K" you picture exhibit a higher than "normal" number of hardness test indents(dimples)? Might be S/N 1661 was on the upper side of the hardness tolerance range.
WR
