Even going with the lightest options from DD or Centurion is only going to shave off a few ounces (assuming same length) while costing you hundreds of dollars for the gear. Strong but light generally means expensive. Is the rail system the only place you can shave weight from or do you have other heavy stuff on the rifle? Optics, mounts, lights, lasers, bipod, etc? What barrel profile do you have? Do you even need a rail system?