I checked the DSA site and found this;
DSA ZM4 Forged 7075T6 A3 AR15 Upper Receiver; 300AAC - DSZM4CBU300SS-D S Arms
The parts look good but I don't have any use for the front sight. I believe there was word that they will be selling just the barrels also -- in the future. I believe I read that they will sell a Bolt/carrier group head spaced to the barrel for an extra $110 over the price of the upper.