No, rechamber the M-4 to fire the 6.5mm X 39mm round.
Is it cheaper to rework a receiver and replace a barrel than to purchase a new rifle chambered for another round? I don’t think the round you suggest has much greater range than does the 5.56.
Clinton order over fifty thousand of our M-14s destroyed while he was president even thought the NATO 7.62 was and still is an excellent round. My preference is the 30.06 cartridge if a new round is chosen to extend a rifleman’s reach.