Technically clear, and clearly written by someone familiar with modern machine guns. The idea of "moving" with some of the listed weapons is kind of silly, though. No one is walking around with an M2 or firing it unmounted (well, okay, if you've got a 24 strength, I suppose so, maybe). Should also include a strength requirement for the minigun (Jesse Ventura was no weakling in Predator).

All in all, it's a pretty good starting point for the use of firearms in 5e, and a good teaser for the full product.