For reasons unknown to myself, the Army picked for their next generation weapons systems, the 6.8/.277 diameter.
IIRC, three different companies have submitted candidates. One is of the teleoscopic design, another a composite shell body with a metal head, and one metal body with a redesigned head, all are supposed to be lighter than current 5.56, more capable, more lethal and able to penetrate next gen body armor.
Semi-autos have their place.
But I would rather see emphasis on skill, marksmanship, first round hits than trying to use technology as a replacement.
I know more than a few guys with tricked out ARs that cannot miss fast enough. And that is not even under combat situations but shooting at the range.