Or more generally, https://en.wikipedia.org/wiki/Flechette https://en.wikipedia.org/wiki/Flechette. Similar to WWI, where old tech (gunpowder, cast metal, etc)

Or more generally, https://en.wikipedia.org/wiki/Flechette https://en.wikipedia.org/wiki/Flechette. Similar to WWI, where old tech (gunpowder, cast metal, etc) was scaled and automated to deliver a new scenario.