To the group..

I believe the theory that these lugers were assembled by Kreighoff from Mauser supplied armours spare parts to complete their second Luffwaffe contract of 10,000 pistols, of which about 5000 were KUs (sorry no umlout on my keyboard). See chapter 5 of Gibson's "The KH Parabellum" for more details. I personally have owned KU3365 a 41/42 with a KH E/2 (proofed inside) matching sideplate. Since Mauser was in the process of switching over to P38 production at this time, even a gentle suggestion from Herr FieldMarshall Goering, to help out the LW, would not have gone unheaded.