Can someone tell me where in the 2nd amendment it says you can carry machine guns?

[Aoi Magi]

In most cases of self-defense a can of pepper spray or other non-lethal methods work quite well. And unless there is some kind of war, I fail to see the need of automated lethal weapons in the hands of common people in a so called civilized nation, especially when other first-world nations are surviving quite well without having every citizen running around armed to the teeth.