Fired a full magazine of Winchester .223, from each mag I have, including the new 10rd lar pistol mag and some hornady 5.56 as well, zero issues except some failure to feed (didn't pick up a round from the mag) on a cross mag. Ran some more of this UMC, jams occur. I'll update once I hear back from the Remington rep. This about settles it, this box of rounds contains a large percentage of NFG.