This is currently unreproducible by me because I'm already affected by it..... but here is my idea of how it happened.
1. Apply Noise Canceling Coating to ranged weapon
2. Equip said weapon at least once with the buff
3. DE the weapon by some means (I used salvage)
4. ????
5. Profit
I've been applying the silence without the augmentation for the last 18 hours. =D