I found out that when I use different weapons and put any other ammo than 5.56 in it and then return it, an amount of 5.56 ammo will spawn in the ammo slot. So it's a bug that could be used to produce a lot of 5.56 ammo.
Does anyone know why that happens?
I use this plugin. That's why I write that here.

Edit: Seems to  be a problem of the Turret Config plugin.