It doesn't work that way.
Say you have 3 items which lower ammo consumption. (I am making up items and numbers, doesn't matter for the example.)
- Endless bullet pouch: 25% less ammo consumption.
- Everlasting pants: 25% less ammo consumption.
- Machine gun: 50% less ammo consumption.
But not really.
For every bullet you fire one of these items gives the chance to not use a bullet.
Say I fire a bullet.
- Endless bullet pouch does a roll, roll fails and the bullet is spend. Or it were, but you have more items with this bonus.
- Still the same bullet but now the Everlasting pants makes a roll. Roll fails.
- Now the Machine gun does a roll. Roll succeeds and the bullet is not spend.
This dice rolling happens every time you fire a bullet and have a less ammo consumption bonus.
You'll never have 100% free bullets. But with more and more items like these you get more and more rolls of the dice to not waste your bullets.
Hope that makes sense. Anyone do correct me if I'm wrong.