Hi Conny, I didn't look at the serial, but the stamps that I was interpreting as JVM stamps were the ones in the ovals, as he marks all his guns this way... JVM made several if not most, of his carbines using 1900 or 1906 grip safety guns...(they weren't that expensive 20 years ago!) But if the frame is not cut for the Martz safety toggle release (M.S.T.R.), then maybe it's just a coincidence... as he might have used this method to make / mark them in the same fashion as the originals... but alas, i'm not too familier with any carbines of the original Luger family ...soooo, the jurys still out on it!
best to you, til...lat'r....GT