Mother Base Gears (needed for trophy "Collector")

[tjoe1bkhjtqxm]

I was thinking that I missed what kind of recipe, opened all the containers in both maps, played plenty of hard and extreme matches, and instead tonight I figure out that I miss only three common (Grey) gears to earn the trophy lol 

 

Actually this thing makes me scared because I have already played 10 easy matches with full group and no drop... I should try on Normal matches?

 

The gears that I'm missing are:

 

-mother base fagitues (upper) 
-mother base field gloves
- mother base fagitues (lower) 

 

Easiest way to earn them? Thank you!