I think a lot of pistol round ARs. SUPER GREAT performance and control for close range work. But, I am not doing any more builds from people selling all of these parts till we start to see some well working proven performance.
Back when I was a MOD on Weaponeer, there a few of these CNC metal milling experts who turned JUNK that did not work unless I spent redesign effort on it. The problem with that is we spent full pop on these parts.
Let's see some finished working units running first. Instead of us providing R&D money and effort for YOUR projects.