I served in the navy of the IDF and something very similar to that happened some years ago. A missile ship had an artillery malfunction during one of their usual practice drills firing their Otobreda 76mm gun, so that the cartridge and the projectile separated while the gun was being released forward, causing the entire weapon to become stuck mid-fire. Because of the complexity of the malfunction, they had to request special permission to go back to base while the weapon was still fully loaded, which is potentially very dangerous.

So when the missile ship came back to shore they brought in some of the most experienced weapons experts to handle the problem. These guys are the real deal - they've been around pretty much since we got our independence and could probably take apart and rebuild machinery like this blindfolded without breaking a sweat. Naturally, they immediately figure out what steps to take, remove the projectile with ease and proceed to attempt and dislodge the cartridge from the tray it's sitting in. Problem is, since the weapon was still in pseudo-fire mode, it still wanted to go forward and fully complete its course, and made it very hard to remove the cartridge until it did. So the men, completely desensitized to dangers like this, decide that the best way to remove the cartridge is to get a hammer and a large screwdriver, and just pound the thing from the rear until it breaks loose. One of them gets on top of the tray and holds the shell while another stands behind it and starts pounding away. As the cartridge is pushed farther and farther in, the man with the hammer and screwdriver loses sight of where it is he is actually hitting and slowly aims closer and closer to the center of the back-end of the shell (where the primer is).

I'll remind you now that this is a cartridge that hasn't been fired yet, so it's still filled to the brim with fun stuff. When the man finally hits the primer, the gunpowder explodes, tearing apart the entire tray it was sitting on and most of its surroundings. The two men handling the cartridge are completely knocked out, completely scarred and severely impaired from the blast. The man on top of the cartridge was blinded in both eyes and required surgery to save his arm, as well as losing most of his hearing and becoming significantly disfigured. Similarly, the man with the screwdriver lost one eye and also nearly his hearing, but was relatively well-off in comparison to the other guy.

I wasn't actually there when it happened but at a base near it, and when we heard the explosion we thought it was just an airplane breaking the sound barrier above us. It wasn't until half an hour later that we learned what happened. Needless to say, the two men left the service and are now living off on disability, and one of them now has to walk around with a seeing-eye dog.