I knew that CNC Warrior was making the three-lug design for ARs and ARMs. I thought that it might have been an earlier design, although now that I know what Valmet gas pistons look like, that was a little bit silly of me.
Any idea when they might have switched to the triangular design? I also wonder if it's unthreaded to save money. (And if it, then, just slides into the bolt carrier and is secured entirely via cross-pin.)