The answer to your question is YES.. 5.56/223/300BLK/350 Legend all use the same bolt head. And yes it does have a rebated rim due to the case head being a bit larger than the 223 Rem cartridge that was stated by Admin earlier. Case head on 223 Is .3759 and 350 Legend is .390 This was done to prevent case head failure.. Hope this helps you out..