Hey guys! I've got you all a heaping helping of High Grade Weapon Parts locations here. Once you've picked one of these up, head over to your nearest work bench, and go to the weapon upgrades. You can use High Grade Weapon Parts to unlock level two and three upgrades on any one weapon per weapon parts.
Chapter 3:High Grade Weapon Parts 1 - 8:13
High Grade Weapon Parts 2 - 10:24
Chapter 6:High Grade Weapon Parts 3 - 31:46
Chapter 11:High Grade Weapon Parts 4 - 43:33
High Grade Weapon Parts 5 - 45:25
High Grade Weapon Parts 6 - 50:09
Chapter 13:High Grade Weapon Parts 7 - 54:22
High Grade Weapon Parts 8 - 54:35
Chapter 15:High Grade Weapon Parts 9 - 1:02:40
In The Lockers:High Grade Weapon Parts 10 - 1:05:16