[ericthered]

By way of example, pretend we have a faux-gunpowder that's super-science. Off of its homeworld, it just doesn't burn fast enough to propell the bullet. So what happens if it goes off world?

If you don't try to burn it, nothing. If you stick a bullet make from it in a gun and fire it, you consume the bullet, and you'll have to take to dead cartridge out, and odds are there will be a mess to clean up before you use the gun again safely, but to really destroy the gun you'd have to abuse it both where it didn't work and where it did.