Also note that the M1 steel pot is not circular around the bottom, its sort of a rounded off square due to the angles and flare of the brim. The steel pot appears to be rather a simple helmet until you try to get the shape right, then its a multitude of angles. Plus, too many guys sculpt it as form fitting like the liner. The shell had to be large enough to fit over the head and a hard liner, so its rather large and bulbous. Since there was only one shell size (the liner did the sizing to the wearer) you can see some pretty large looking helmets on small heads.