Ha Ha, the fuze should be on ARM to make it more interesting.
As to a story:
In 1972 (as can be seen from the serial number) a special project was set up as the answer to the plans of the Warsaw Pact forces.
The only way to stop the rolling red force was nuclear ammunition.
(There was an secret information that the russians are researching something similar to tame the chinese dragon)
Theresearch was sucsessfull, but at the unit trials it was difficult to make the soldiers fire the mortars. They bluntly refuzed to fire it.
Thanks to some logistic problems, couple of the crates of unused ammunition went to a store of an unnamed AFB.
10 years after decomisioning of the base the ammo was found under rubish, old furniture and old boots.
Someone who was not so smart put them on ebay.
If You make an offer on ebay, someone might come to your door.
I am not sure if THEY will knock
Bob