Machine-made nails have a roughly rectangular cross-section, when viewed from either end.
In production a nail is sheared-off alternately, from FLAT iron stock, then run though the heading process,
which leaves the head still rectangular, but with the thinness of the SHANK, resulting from the gripper, starting just below the head.
These are correctly called "CUT Nails".
Hand-forged nails start from SQUARE stock, have very definite SQUARE-shaped heads, of which often have a faceting-
appearance, or simply looking Rose-headed....our true "SQUARE-HEADED nails".
See attached about some early nail making, taken from:
A Museum of Early American Tools
by Eric Sloane
