Thanks John!
I had noticed, at some point, that some Lugers had a noticeably thicker rear 'ear' abutment, but didn't know the significance of it. I don't have a pic of those (the 'reinforced' ear) but the rear abutment was thicker than the top/front.
My 1937 S/42 Luger has the 'unreinforced' frame. Two other Mauser Lugers I have, have the 'humped' frame. I don't have a 'reinforced' frame (130mm without hump).
