Anyone have details?

Right now, as far as i can tell, that one is a custom one-off. The one i have from CNC is DI and when talking with the developer, it took quite a bit of trial and error to get the gas port positioning calibrated for the x25 energy. Compared to a standard 223 round, its got a lot less gas and so the port is just under 2 inches from the barrel nut (if that gives you any indication). With that, you can see why most pistol uppers are of the blowback type. A piston system might have the on-paper advantage of cleanliness but so far, i've not had any issues with about 1000 rds of surplus through mine. everything of importance is stainless and you could have the BCG Ni-coated or maybe treated with fail-zero for added protection there.