from your side elevations diagrams the 5196 and the 6196 have the protruding 'finger nail' between the 6 lugs for opening the case back-are they hinged?-where 6119 does not.
6119 having a standard snap back hence can be thinner along with the flat glass back and front.
calibre 215 and 30-255 are both the same height at 2,55mm.