As a follow-up to a previous discussion on this topic I recently purchased the German version of Vom Stahlhelm Zum Gefechtshelm by Ludwig Baer. On page 103 there is a picture of two original M-18 cutout helmets. One of the cutouts clearly has no step. Interesting enough, my other reference German Helmets 1933 to 1945 by Goodapple, Maertz and Weinand indicate on page 10 of their reference book that "the six metric shell sizes remained the same for the M-17 and M-18 Ear Cutout shells". I have a scanned version of page 103.
