How should I go about gun ammo? On the server or on the client?

Well when you have an FPS that makes the player have to reload their gun in order to kill their enemies, there's always gonna be a player who exploits it and has infinite ammo.

Now If I handle everything that is important in one LocalScript and everything that is not important in a few module scripts like animations, GUIs and more should I be safe from exploiters making infinite ammo?

If I handle it on the server which prevents that infinite ammo exploit which is great, but then causes input lag which isn't so great for the clients.

What method should I use and why? Is either good?