Resident Evil 7: Biohazard · Unlockable weapon bonus
Infinite Ammo
The unlock guide lists Infinite Ammo as a bonus unlocked by completing the main game on Madhouse difficulty, without further item details.
How it works
The guide states that completing the main game on Madhouse difficulty unlocks Infinite Ammo. A separate gameplay description says bonus items can include infinite-ammo weapons and can be added to item boxes for subsequent runs. The sources do not identify which weapon receives this property or detail how the unlock works in use.
Read the supporting references
Steam-Community :: Guide :: Resident Evil 7 Overview of Unlockables Resident Evil 7: Biohazard - Wikipedia
Check the edition and source version for patch-specific details. Guide methodology.