If the grenade bodies were manufactured and not marked at the time of manufacture, that process would deviate from most if not all other government contracted munitions. If the non marking was due to cost reductions during war time I could understand it but not as something omitted from the manufacturing process just because the munition was not loaded. The designation had to be known when the bodies and internal parts of this grenade type were manufactured.
The picture I supplied to this thread previously seems to show characters that were stenciled on. I don't know the history of the item in those pictures so I can't say with any certainty that it is an accurate representation of the technique used to label the M9's. I would assume that the labeled characters would be more distinct and cleaner looking; however, the following may have some relevance to this?
RECOMMENDATION OF THE ORDNANCE COMMITTEE MEETING
HELD 12 October 1942
That all H.E. bombs and separate loaded H.E. ammunition be painted with lusterless olive drab paints containing available infrared reflecting pigments. Formulas for suitable infra-red reflecting paints of adequate stability and which do not contain critical materials, are available and will be incorporated in the specifications.
b. That other ammunition, fixed ant semi-fixed rounds, rockets, grenades, mines, etc, except Small Arms, remain as they are at present with the following exceptions:
I. That all colors used on ammunition be lusterless instead of the present semi-gloss, to dull finish.
II. That the yellow color now in use as a base color on H.E. ammunition be changed to a lusterless olive drab with No, 4 yellow stencil to designate H.E. filler.
III. That all wooden ammunition boxes used in the transportation of ammunition to the using services be stained a light brown color to decrease their visibility.
IV. That all metal parts on the exposed portion of the ammunition boxes and containers be painted with a light brown lusterless enamel.
c. That a lusterless color card be prepared to show lusterless color including infra-red reflecting colors, for use on ammunition, similar to the present color standards issued in connection with specification No. 3-1; General Specification for Paint, and Related Materials.
d. That current stocks of artillery ammunition packed in fiber or other containers in which the ammunition is issued to troops need not be repainted. Current Stocks of separate loaded ammunition will be repainted if and when practicable. Current stocks of bombs, which are now painted with lusterless olive drab without infra-red pigments need not be repainted. Current stocks of rifle grenades, hand grenades and rockets in depots will be repainted to conform with these recommendations.
Stocks of rifle grenades, hand grenades and rockets in hand of troops will be repainted if and when practicable.