Krieghoff - what do I have here?

[Tom Whiteman]

Ok guys,.... what the heck is it?
I think I have a post war, GI put together gun, but looking for imput. Sorry for the lousy photos, but hopefully we can get an idea on this gun. Seems like Mauser frame, 42 mark on toggle. What parts are numbered are matching, but most are not marked at all. Sideplate, firing pin, hold open, trigger, take down lever, safety lever..... all have no markings. AND the mag is BW style, but no markings either. So...... what's up with this?