Darwin Award honorable mention nominee! (I think you actually have to die from your stupidity to be considered for the full-fledged award.)

My uncle did something like that when he was a kid. With ammuniton he and his friends found in the woods shortly after a NATO REFORGER exercise at the end of the 60s.

His glass eye is still a great attraction on every family celebration.

The unanswered question is what he was thinking (so why were you hammering bullets?) It's really not effective without that . . usually it's the punchline and the best part of the story.

However, a search for "hammering bullets" reveals this is not an isolated incident.

Just last year [poststar.com]

...Police said Mosher told them he was trying to empty the rounds so he could return the brass casings for scrap. He had set off approximately 100 rounds before being struck . . . . An employee of Capitol Scrap Co. in Albany said Monday that the business pays $1.70 a pound for scrap brass shell casings....

Beer money?

...a similar case years ago where a man in West Glens Falls who kept a .22-caliber round in the brim of his hat discharged the round when trying to swat a bug with the hat....

The symbolism here is priceless . . .

My grandfather hit a 12-gauge shotgun shell with a sledgehammer when he was young. It was Independence Day and he couldn't afford fireworks. The story would likely have ended fatally and I wouldn't be here to tell it, except that he fortunately thought to empty out the shot first.

He blew a large chunk out of the sidewalk in front of his home and the sledgehammer was knocked back up over his head. For one reason or another, he never particularly cared to do such a thing again! ;)