If you look closely at the CA NG, they are carrying magazines in their pouches. My Army friend said it is against regulations empty mags in their pouches.
So, where do you carry a magazine after you empty it?
During my time in the Army and National Guard I had two full 20-round magazines on me at all times I carried a rifle - even the one time I stood guard at a German base entrance while Red Army Faction sympathizers threw rocks and bottles at us and we were ordered to do so without ammo.
That was some training from the last Vietnam veterans still in the service then. “Learn the manual but remember what we tell you if you really want to survive”. They lived by the old fashioned notion of Lead By Example. Bless their souls.