In basic, we were issued real rifles about the third week, when we got TA-50, and from that time on, we were in web gear, rucksacks, helmets, and carrying rifles everywhere, except to PT and meals, when we grounded it outside the chow hall, and left two guards. We had empty clips in our ammo packs for the feel of them.
We got issued actual ammo only just before firing, and turned in the clips right after, and the drill sergeants rodded our rifles to make sure there was no round in the chamber.
If you tried to pocket a couple of extra rounds (so that when you qualified, you had extras to fire), and got caught with them, you’d get severely disciplined. A second offense could get you recycled (restarted in basic). There was an amnesty box in the bay of our barracks, so if you discovered a round, or even just brass, that had fallen into your cargo pocket accidentally, or something, you could dispose of it. You could also throw away any rounds you might have tried to sneak out of the range, then thought the better of, in the amnesty box. Stuff really did happen. When I had detail filling clips, and I handled hundreds of rounds in an hour, I found one in my pocket later that day, and threw it in the amnesty box first chance I had.
When DH was in Iraq, he carried a rifle and a full clip everywhere, but the clip was not locked into the rifle; in was on his ammo belt. He did NOT have a round in the chamber. He was on a secure base in Belad the whole time. Infantry on patrol probably had a different procedure.
We always had complete rifles, though, with bolt and firing pin, and had to disassemble them and put them back together every evening, until no one asked any questions, and we could all do it automatically. We had to clean them thoroughly after firing, and they got inspected. We also had to clean them if we’d been crawling through sand or mud, or if it had rained that day.