How do I stop a action?

How can I do one of the following:

When the ammunition runs out the player cannot fire for a few seconds and only after that time when the player has "loaded the weapon" the ammunition is renewed and he can fire again.

or:

When the ammunition runs out, the player can't fire until he finds boxes of ammunition on the map.

You can sum it up this way: How can I stop a certain action for a certain time?

You need to add a condition that if ammo > 0 => do shooting.

Then when you are out of ammo, the actions behind won't be executed.