It wasn't the part that takes the highest stresses, but it -is- the part which is identified as the firearm in the US - sort of like the motherboard isn't the component of the computer which takes the highest stresses (that would be the processor), but is the part which is recognized by an OS as the computer. Additionally, it takes little machining skill to finish the gun from that point out of supplies you can find in most hardware stores. (Much less assembling the rest of the gun out of unregulated parts.)
Smokeless gunpowder is only desirable if you care about being spotted. Regular old gunpowder is easy to make (my chemistry lessons from my father - I was homeschooled for a substantial portion of my childhood - were very practical, and this is one of the things I learned to make.) and perfectly practical for just about every application you could want it for. Additionally, guncotton does not in fact require nitroglycerin; that's only one of the two types that can be produced. (It invariably requires large quantities of nitric and sulfuric acids, however. Nitric acid is harder to come by than the raw materials for gunpowder, especially in the quantities needed, which will generally attract law enforcement attention. It's not impossible to produce yourself, but difficult.)
Given that the firearm creation occurred some 50 chapters before what I'm writing now, and the result was successfully used for at least one plot-point, it would be a bit impractical to revise it just now. However, I can still keep these notes in case I do an eventual full rewrite; and these comments can be useful for filling in some as-yet-undescribed blank spots, such as helping to explain why none of the other game-pieces have managed to assemble their own modern firearms.
In case it was buried where some LessWrongers here didn't read it, the point in th...
For the past two months, I've been writing, and posting, roughly two thousand words a day of "Myou've Gotta be Kidding Me", a story set in a "My Little Pony: Friendship is Magic" fanfic universe, "Chess Game of the Gods". Outside of the sheer NaNoWriMo-like exercise of pushing out near-daily chapters, I've also been trying to keep in mind the various principles I've learned from Yudkowsky and LessWrong, and to try to present them in a way that people who like reading MLP fanfics might be able to appreciate.
I've just come to something of a minor climax with chapter 60, and while I'll definitely be continuing the story, this seems like a good time to mention it here, for whatever feedback and constructive criticism anyone cares to offer.