Yesterday I was told to stay AWAY from Hornady Ammo. It IS Not to the original Rem specifications. Hornady is using a different "longer throat" on their ammo. A good friend has an AR-15 in 6.8 SPG, and has been having problems. Ty, if you see this post you may want to check out some Hornady ammo to see if there will be a problem in the XCR. I plan to use only Remington brass which has the large rifle primers. Silver State brass uses small rifle primers. Mix your brass and you are headed for disaster. I am using Remington 115gr bullets (both FMJ and SP), with 23.5 gr of H4198, Federal Gold Match primers. When I get my barrel kit for the XCR I will pass on the results of this load. My info off LoadData gives the same 23.5gr for IMR 4198. Have a great shooting day. Jack