While digging through the IAA Forum (an excellent resource for the cartridge collector) archives for data on the 7.65 Argentine, I came across these two threads chronicling two separate instances of spotter ammunition detonating while using an impact puller to remove the bullet! Yikes!
“Spotting” or “observation” rounds as they are called are distinct from tracers in that they contain an explosive charge as well as a percussion cap and an inertia firing pin inside the bullets themselves. These rounds, similar in construction to those tested in a recent episode of InRange TV against ballistic soap, were used for marking the impact of a machine gun to allow for proper dialing of T&E mechanisms, similar to how artillery pieces were aimed during the same time period.
Naturally, it’s not a fantastic idea to go smacking a round like this against a hard object. Unfortunately, sometimes mistakes do get made* and the result speaks for itself. Fortunately, so far as is known, no one was injured in either of these incidents – probably thanks to the long handle on commercial bullet pullers.
*In particular, some 7.65 Argentine spotting ammunition is marked only by a black painted tip – similar to the markings used by most nations to denote harmless (to the collector) armor piercing ammuniton. It’s easy to see how this ammunition might get mixed in with, or mistaken for ammunition with an inert projectile, and lead to an accident if the owner wanted to pull the bullet.
Stay safe, everyone!