Right after 9/11 the guards around post and in the airport had M16s w/o magazines. Soon they had a mag in the weapon and the safety on. Since you can not engage the safety on an M-16 unless the hammer is cocked (at least it does on my AR and from what I remember about the M-16 a few years ago), this implies that the weapons are loaded, round in chamber. Otherwise I would think that they would have an empty chamber, drop the bolt and hammer, and just insert a loaded or unloaded mag to give the impression that the guard is ready to fire. In that case the safety would be off since the hammer would be down. Maybe they have the gun cocked but still no round in the chamber, with a loaded/unloaded mag in the rifle, just so they can have the rifle on safe but still not be loaded, but that seems to be beyond most guardsmen/MPs/hospital techs impressed into guard duty. LAter.