This is a good 4 years too late but I'm working on a project looking at how modern technology survives a 'soft apocolypse' (ie 99% of the population just evaporate, the idea being that its so generic that its widely applicable). I chanced on your post researching making smokeless powder, my current estimates suggest guns will last for hundreds of years but although ammunition will last at least 50-100 years but it will probably be used up in 10. My blog is over on OMG, the moderator removed the link to my blog because it's against the rules! (but they probably don't mind a non-commercial link in my signature) and email is mjlush at gmail dot com, I'd be very interested to hear your thinking/research on the matter.
