At an estate sale I bid on and won 2 boxes of what was stated as PMC 223 AMMO. After the sale when I got my prize in hand I noticed the boxes are marked PMC 223 A/D 5.56MM BALL M 193. On the side of the box it says made to U.S military specifications. The cases are head stamped 223. Being this is head stamped 223 I'm thinking it is safe to fire out of my 223 rifle but I want to be 100% sure. Any info on this ammo would be helpful .