Rifleman carry ammo resupply and on pretty much any game mode setup you shouldn't have a problem finding ammo in general, but I do understand that AI only with one human player as a unique kit is an issue. That should be resolved long term when you can request ammo from AI or if other systems take over.
With that being said, main base could have an ammo resupply as a match based economy system leads to a much different game mode/style that needs to be designed as oppose to just resupply the player.