Custom Parts are crucial for upgrading your weapons and tailoring them to your playstyle. These parts can be found hidden in the environment, dropped by enemies, or purchased in Raid Mode. Each weapon has a limited number of slots for custom parts, so choose carefully.

Common Custom Parts:
| Part Name | Effect | Notes |
|---|---|---|
| Damage | Increases weapon damage. | Essential for all weapons. |
| Fire Rate | Increases rate of fire. | Great for handguns, machine guns. |
| Capacity | Increases magazine size. | Reduces reloads. |
| Long Range | Increases damage at long distances. | Ideal for rifles. |
| Close Range | Increases damage at close distances. | Perfect for shotguns. |
| Full Burst | Fires multiple shots per trigger pull. | Massive damage for shotguns, machine guns. |
| Auto Loader | Automatically reloads weapon. | Very rare, powerful for magnums. |
| Dodge Master | Increases dodge effectiveness. | Good for survivability. |
| Grenade Launcher | Adds a grenade launcher to a rifle. | Requires specific rifles. |
| Charge Shot | Allows charging a shot for extra damage. | Slows down firing. |
Custom parts can be swapped between weapons at any item box. Experiment with different combinations to find the most effective setup for each weapon and mission. Higher-level parts offer greater bonuses.