Just about all manufacturers of 223 civilian rifles warn against using Military ammo in their guns. The black guns maybe an exception. As Stimpy pointed out , they usually do not shoot very well. Those full metal jacketed bullets are not known for their accuracy. If it was me, I would pull them down, dump the powder and save some bullets for sighting in, and discard the rest. Then use the cases for new loads with powder and bullets you can get over the counter. After firing them the first time, punch out the primers and clean up the pockets and start over as if fired once in your rifle. You could sell them if you do not reload and buy civilian ammo. You will not get as many rounds, but at least what you get will be safe and much more accurate. Stay away from foreign makers of 223 ammo as well, usually they do not do well either. Just my 2 cents worth