Guide to modifying weapons in Metal Gear Solid 5 The Phantom Pain
Weapon customization is an almost hidden feature of Metal Gear Solid 5 the Phantom Pain that is unlocked only after completing particular tasks.
After unlocking this feature you can customize your weapons in the ACC directly from the iDroid. Here's how to do it:
FASE1: Complete OPTIONAL mission # 107 "Extract the Legendary Gunsmith". This optional mission becomes available after main mission 13. It is usually not found right away because there can only be a limited amount of side quests per area at the same time. So, if you don't find side quest # 107, keep completing others (especially in Angola, Zaire Border Region) until it pops up. If you have difficulty completing this mission, watch this video.
STEP 2: Complete OPTIONAL mission # 108 "Extract the Legendary Gunsmith again". This should activate automatically after completing # 107 (go back to the ACC and it should be available). If it is not available, continue to complete other optional missions. Some users report that it was unlocked for them after completing optional missions # 06 and # 48. If you have difficulty completing this mission, watch this video.
STEP 3: Complete OPTIONAL mission # 109 "Extract the Legendary Gunsmith One More Time". This is the last part of this little questline. Same as before, # 109 will become available after completing # 108. If you have difficulty completing this mission, watch this video.
Now watch this video to see how weapons can be modified:
Just go to the "Mother Base" - "Customize" - "Weapons" tab and choose the type of weapon you want to create. To get new parts you need to develop more weapons, the parts of each developed weapon will be available for customization. Don't forget to consult the cheats / complete guide card of Metal Gear Solid 5 The Phantom Pain for other useful guides on this game.