First you must complete the game once, after you complete the game you can access the Extra Content Shop which can be found under bonuses, this shop uses a currency called CP. You can earn cp by completing specific challenges in the game, keep in mind they are different from the Lei currency.
To unlock the infinite ammo available for purchase, you must also unlock all the weapon’s customizable parts.
Most parts can be bought from the in-game merchant, but some are found elsewhere in the game, so the first step is to create a manual save in the game, preferably next to the in-game merchant. Keep in mind that before you can get Infinite ammo, you have to unlock all the customizable parts for your weapons.
Here we’ll unlock Infinite ammo for the LEMI. We still need one more weapon part, but this part can be bought from the Duke. Now we have all the customizable parts for LEMI, and if you open your inventory, you can check if you have all the parts, the dots under the weapon shows how many parts are available. Once your weapon is fully upgraded, you can buy Infinite ammo in the Extra Content Shop, then save the game again in a different slot, do not overwrite the previous save.
Quit back to the main menu and enter the Extra Content Shop, scroll down to LEMI or whatever weapon you have upgraded. Buy it with cp to unlock the infinite ammo.
Go back to the main menu, load your first manual save before you upgrade anything, and you’ll still have the LEMI with Infinite ammo in your inventory, but you’ll also have all your money back.
Do the same thing again with a different weapon, just make sure you have make another save before you quit to the main menu.
This method will definitely save you a lot of time if you want to have Infinite ammo with all your weapons, but keep in mind that you will still need a lot of CP to buy Infinite ammo for all your weapons.
