This is the schtick to ignore ammo restrictions.
Many action movie heroes appear to be able to fire their guns constantly without ever seeming to reload or keep track of rounds fired. Actually, they're reloading so fast that you can't see them, having bought the Lightning Reload schtick.
You load up guns very fast. Any weapon that normally takes three or fewer shots to reload can be reloaded in no time, and weapons normally taking more than three shots to reload can be reloaded in a single shot.
You never run out of bullets, no matter what the situation, no matter how improbable. Enemies, events and accident can still take your gun and ammo away from you, though.
No matter how fast you reload, you cannot shoot more than the entire ammo capacity in one action.