There is/was a Missouri Bell at one time; had the individual companies in most of the states. I did find a Bell System axe head in a generic search of the web and the info i read said it was manufactured by Stanley probably between 1940 and 1960. The example pictures almost all have a square cutout in the cutting edge and no hammer head and it appears that an axe may have been made, also. I know it's messy, but you might try filling the low areas with chalk and re-photographing that thing.