In keeping with Gary's question below:

working at the radio station across from Ft. Campbell, one of my hunting buddies was an officer on base. Quite often he would call me at the radio station and ask when did I get out of the station. I had the morning show so I was out by 1 PM. he would meet me at gate 14 on post and we would go shooting. One time he took me to a huge Quonset hut to get a few guns and ammo to do some shooting. Looking at the guns stacked there, many of which were in the process of being shipped to Viet Nam with the 101st. Along one wall were hundreds of wooden crates stacked top to bottom with loaded M-16 magazines, probably 50 magazines per box. Some of the dates on the boxes were 5 or 6 years old. My friend said they came came fully loaded and ready to be used once they got to the forward operating base. After that i never worried about keeping my magazines loaded. Long story with a short answer.