djs,
After a few hours?
For any engagement we had while I was carrying a M-21(operation Urgent Fury) their were no extended hour-upon-hour firefights!
When you engage or are engaged you had best have a accurate grid location as doctrine teaches when you are able to,you destroy the AO with ARTY,CAS or Navy 5"(too bad no more 16",sin loi to all those unlucky basstruds who had those fall on em)
If you had the 82nd with you then you could ask for the 3/73rd for support with their M-551 airborne assualt vehicle and it's 152mm main-gun.
If all else failed you had 81mm or for sure 60mm motar's for indirect fire.
Nope no more "trench-warfare were your stuck firing "static-position" for hours!
Unless you want a 60mm/81mm/120mm motar,105mm/155mm howitzer or plain old BLU-84's to rain hell on you.

If your on a shoot-an-scoot and your resupply is days away,well then whatever the local-troop is issued would be a prevelant choice.
Easier too to sound like the bad-guys and resupply is somewhat better.
Most troops have mission that dictate that they carry a resupply in their alice/molle but others have to carry other mission-critical equipment.
My ruck was never able to carry the amount of ammo that others did as my task was "area-denial".
You need a road or trail closed!
You want to funnel troops into a ambush.
You want to make any unit pay who is following.
Buildings opened,bridges closed.
My job was the engineer tasked to the 75th Regiment!
I started out as a 11B1V,made E-5,went to "Lost-in-the-Woods" and got my 12B.
Carrying demo and mines does not lend a large alice much room for much else!
Mike