This is the T-9 mortar nose fuze, which became later on the M45 mortar PD nose fuze. I don't have an exact time for the T-9 but I guess around mid 1930's. The M45 was also used before/early WW II. The fuze is made complete of brass or aluminum, with the delay/superquick impact action selected by turning the upper fuze head into the desired position. This is also a fuze from the MTRC reference collection.
Enjoy
Mrfuze, USA
Enjoy
Mrfuze, USA
