Quoted:
I've never heard of such a thing.
Anyway, smokeless powder is primarily nitrocellulose, which is essentially what you get when you expose cotton to nitric acid. There's no mercury in it.
There shouldn't be any in the other components of smokeless powder, either, unless something got contaminated.
Black powder MIGHT have trace amounts of mercury in it but I do mean TRACE amounts.
Primers used to have some mercury in them but non-mercuric primers are by far the rule rather than the exception these days in modern ammo,
though older, foreign made ammo can be mercuric and you'll know when you find it because if you shoot the stuff and then don't clean your barrel afterwards,
the next day you've got a pitted ruin that was once your barrel.
CJ
<===== Chemist here
cmjohnson has it pretty much right.
Smokeless gunpowder is primarily nitrocellulose.
It also contains some nitroglycerine (double based powders) and other burn-rate-modifiers.
The individual grains are also coated with graphite to make it flow better.
PURE nitrocellulose is clear. Old movie film was nitrocellulose.
It was one of, if not THE first plastic ever made.
I even remember that some plastic screwdriver handles were made of nitrocellulose.
Pingpong balls are nitrocellulose based.
As far as primers go, mercury fulminate was used as a primer.
Then there were lead compounds, which may still be used. Not sure.
I've read that "corrosive" ammo was only corrosive because the primers' combustion residue would absorb water out of the air (hygroscopic).
Little droplets of water could form in the action/barrel, and lead to rust. It wasn't because the residue was acidic.