I’m curious why they are are so stuck on the 16” barrel. If it’s overall length of the platform, you can go bullpup and have a much longer barrel for ballistics purposes and still be in a “standard” chambering that can far exceed the 140 grain bullet at 3000fps. Seems like an answer to a question nobody had asked until SIG or the military decided this is a must have capability. Barrel life and the potential of failure with a three piece case design would be a major concern as well. Dissimilar metals of the case over years of storage could easily lead to case separation and get a person killed in a battle with half the case still in the chamber. Maybe it will be the greatest thing ever but count me skeptical.