At any point do they explain the benefit of triangular rounds? How do they keep the barrel from overheating like they do in other high-volume projectile systems? Is that the benefit of the open chamber?

Looks to me like the only benefit they're claiming is that the mechanism is mechanically simpler. That's probably a reasonable benefit, but they've had 100 years to perfect more traditional guns so I imagine there would need to be a pretty substantial advantage to be worthwhile, particularly since it needs special ammunition and all the faffing about with supply chains and inventory that it would necessitate.

It's possible the open chamber would help heat-wise by preventing the bullets from "cooking off" which is a problem with some machine guns that happens when the chamber gets hot enough to ignite the propellant making the gun run away, firing without the trigger being pulled. That wouldn't apply to an electrically (or whatever) driven gun like this, though.

So... yeah, it's probably just one of those "let's try it and see what comes of it" sort of things, because I don't know why you'd want a gun with funky ammunition that takes up more space because it might be slightly more reliable than the otherwise very reliable existing guns.

Yawn..., pretty boring stuff. Don't know why I would ever need this info. Guns and killing stuff..., No time for this ...