You're trying to explain a futuristic technology with current technology. Seeing as how when you load a HC they don't shoot a tradition bullet in the sense you don't see bullets in the back of the cylinder. Also if you look at the bore of HCs you will see it's quite large. So how is a cylinder of say even the hawkmoons size holding 12 of those projectiles in a cylinder that size? Fact is its not holsing those bullets because it doesn't shoot bullets like our guns do. You're assuming it has a fire pin to knock on a trimmer when theirs no indicatuon of thay on the cylinders itself. I would assume it's rotating the cylinder and it would be an electronic firing pin. So when the hammer drops it sends an electrical pulse to fire the gun. As for the LMG, their are some top loaded machine guns like the bren. So what if the ammo that is going in the above the barrel is going straight down into the bolt? It seems silly but if they have access to materials for slick parts and very good lubricant to prevent jamming and say on some of the mags it has a an assisted electric motor to help load the rounds so its not purely the action pulling them in the chamber than it's entirely possible. Impracricle but then again we don't fully know how their technology works. As for thr scout rifle, idk.