Was shooting 73mm RR (anybody else remember those?) from the prone on range 44 back in 1980. Hit the road-wheel on a M113 hulk at about 150yds.
On impact, the round detonated and the aluminum fuze assembly came straight back at me and impacted the sand right under my chin. I didn't even have time to shit myself, it happened so fast.
Dug it out of the dirt. It was a light, blast-formed lozenge about as big around as a silver dollar and as thick as my finger. Had the green paint from the road-wheel impressed into the front like it had been painted there. Carried it around in my pocket as a good luck piece for years. Still got it at home somewhere.