It's funny you mention that. The seller told me the blade was 5/8 but it sure looked smaller than that. When I get the razor in hand I'll have to measure it but I'm assuming it's going to turn out to be 4/8 like you said.
I had the same thing happen. The last one I bought was suppose to be 5/8 but it was smaller then my other two. I never measured them, just guested and never really compared them to my other 5/8