eli5 Why weren’t machine guns possible to make in the past?

Question

What stopped 18-19th century armies with guns from being able to create automatic weapons like AK-47s and Uzis?
Since they don’t use electricity I feel like they’re made with materials and technology that was already available in the 1750s, surely they could’ve put their heads together to create a machine gun and just annihilate any ops…

Thanks

In: Engineering

Answer 1

There’s steel, and then there’s steel. It has to have the right characteristics. That’s getting each piece right. Then there’s tolerances – how much too big or small the pieces can be, so they fit together but still move where required.

Then there’s the ammunition…