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

You’re missing a few things in 1750.

First, mechanical precision. The kind of machining needed to repeatedly make weapons that work well without jamming required innovations that would come later in the Industrial Revolution.

Next, cartridges. Automatic weapons load premade cases with consistent dimensions. You can get away with a lot more variation in cartridges in muzzle loaders, cranked guns or lever guns than an automatic loading system. You do see weapons like that in the 19th century before brass cartridges. Those cartridges wouldn’t be perfected until the mid 19th century.

Finally, the powder available. Black powder fouls guns very rapidly to the point that ~~musketeers would be equipped with a set of shot that got smaller each shot~~ musket balls were made smaller than the barrel to ensure soldiers could quickly get it down the barrel. Automatic weapons usually capture some of the explosive gases to work the mechanism and these fine, thin tubes would be fouled almost immediately by black powder. Smokeless powders would only be developed in the late 19th century.

Edit: correcting per /u/BoingBoingBooty