Dilandu
I'm dissatisfied, which means, I exist.
Not exactly realistic, because powder... well, it's just not very nutritious. It is probably possible to construct some fungi or something capable of digesting powder, but problem is, that it would not be able to live on powder alone. And gun ammunition aren't exactly the environment rich with nutrients. Not to mention, that its quite dry, and microorganisms did not like dry environment at all.Tell me how realistic this scenario is: a powder-eating bug is spliced together...with soldiers' rounds 'immunized' with toxins that make their rounds even more lethal. Would it work at all? Or backfire with us all back to crossbows?
So, basically you could create bug, that would be able to eat a powder spilled into puddle. Hardly more.
And no, cancelling the powder just would led to search in alternative ballistic explosives. There are quite a lot of solutions that could be used instead of powder; they just aren't, because they are more costly or less efficient.