I was stateside 76-78 and overseas 79-81 in the Air Force and in both places we carried a full magazine in the weapon and three full magazines in our belt pouches. When we carried a side arm, it was always fully loaded. This is not counting the M-60's and grenade launchers we carried when overseas.
It could have been a Homestead thing. The place was a joke. The flightline was protected by the usual “Use of deadly force...” signs, painted on the tarmac, and a perimeter rope about 4 inches off the ground.