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

Three things, mostly:

1. What precision machine tools existed in that time period were very rare and expensive and also just not all that precise.
2. Poor materials science meant that metals were more brittle or just plain weaker and couldn’t handle the high thermal/stress load.
3. It was difficult to mass manufacture parts and especially ammunition – the first cartridge was invented at the turn of the 19th century but even then it was paper and couldn’t be manufactured in bulk like brass cartridges can be.