One good thing about being imprisoned: It certainly gives you time to pursue your hobbies. Whether that's tattooing your eyeballs, brewing toilet DXM or writing threats to your crook lawyer, the specifics are up to you. But some guys, well, they make a little better use of their time. And some take a break from all the shankings and shower rape to change the damned world. Like...
5David Marshall Williams Changes Warfare
If you're extra good in prison, you might earn yourself some Spork privileges. No more eating pudding with the folded up lid for you; you've earned the right to use utensils, son! But that's only if you keep your nose clean, stay out of trouble and generally go out of your way to make prison life more bearable for all. So how good do you have to be to earn gun-building rights? You can ask David Marshall Williams that question, he spent most of his prison time building, testing and refining new types of machine guns.
Caledonia State Prison in (you guessed it) North Carolina thought it was a perfectly fine idea to allow a man who ran an illegal whiskey distillery (and who gunned down a deputy sheriff for trying to shut down said whiskey distillery) the tools to manufacture firearms.
We suspect he is responsible for this bottle design.
After several years of generally MacGuyvering shit for his fellow inmates (and sometimes even the guards), the superintendent allowed Williams access to the machine shop where he immediately began experimenting with new kinds of firearm components. Rather than the thorough Taser colonic he would've received if he tried that shit in modern times, Williams was allowed continue and went on to invent the short-stroke piston and the floating chamber. Unless you're a card-carrying member of the NRA, you probably don't know what those are, so let's just say they made rapid-firing guns even better at taking down a whole room full of people at once.
Without Williams, the terrorists might have won.
These were not minor innovations. In fact, they were so important that he used them as leverage to get himself out of prison, whereupon he returned to the military--no small feat considering he had been kicked out twice at that point.
His components became the basis for the M1 carbine. Even if you're not a diehard gun-nut scrolling through this article by manipulating your mouse with the butt of a revolver taped to another, larger revolver, you've probably heard of the M1 carbine. It was basically the first iteration of the modern war rifle, and it absolutely revolutionized the way battles were fought from then on. If you think it's a little scary that convicted murderers are allowed to manufacture and sell weaponry to the military from prison, please realize this was truly the best-case scenario. Because when you hear the phrase "invented a new super-rifle in prison" it's usually followed by the phrases "bloodbath the likes of which the world has never seen" and "vowed revenge on Captain America."