Hi all,
I think this can be another vague description of the achievement, and people have been reporting it glitching and not popping for them. At first I had problems too and finally unlocked it today. The thing I have noticed is that all six pieces of equipment have to be used in THE SAME PLAY SESSION. Even if I went back the the menu it didn't unlock.
So in short, load up a checkpoint, such as the one mentioned in the other solutions, find the equipment box then use the following all in the same session:
Breaching Change
C4
Incendiary grenade
Frag grenade
Smoke grenade
Flash bang
Hope this helps.