Aero Precision has been teasing this prototype lower on their Facebook page for a short while now. It’s completely skeletonized to cut the weight without going the polymer route.
They’ve put together this video to prove that the lower is reliable even in harsh working conditions. It stands to make sense: big holes let things in, but they also let things out. This isn’t a fighting rifle, anyway, it’s more of a cool looks thing.
Personally I’d love to see this wrapped in carbon-fiber or cast in a clear resin. Best of both worlds.