Insurgency: Sandstorm

Thanks to SMKR 88 who discovered this:
As always play Coop!
Simply throw your own grenade at the ground, pick it up and throw it at the enemy.
I used the M67 grenade while playing as insurgent! Maybe it only counts while using the other teams frag grenade, that means when you are playing es Insurgent you need to use the Security frag grenades and when playing as Security you need to use the Insurgents frag grenade (this is not confirmed, but just my guess).
For Class: I simply took the rifleman with max. grenades
Have fun unlocking this, worked for me at the first try!

Just got this myself. Credit goes to u/LuluFedhund from an old Reddit post.

So here's the trick, you can throw your teammate's live grenades at the enemies and they also count for the achievement. Plus it works in PVE.

So what you want to do is: get a friend and yourself together in a PVE game, both max out your grenades (You need the heavy carrier to have 3 grenades) Then just go out into the game and throw live grenades on the floor in front of your friend and let them pick it up and re-throw it toward some enemies. ( you pick up live grenades by pressing Y while looking at the grenade)

It can be abit of a hassle, especially with Co-op teammates shooting people before you can get your grenade in there, will be abit of trial and error. Apparently, you can pick up your teammates IED and just suicide into enemies, but I can not confirm this.

Credit to the original reddit post, also a video included: https://www.reddit.com/r/insurgency/comments/hijk7l/discover...

I found out a simpler variant.

If you are about to enter a room where there are enemies (staircase down or stairs also goes up) just throw your own grenade in front of you at a short distance in front of a wall ..then pick it up again..and then throw it up or down into the room ..or stairs !!

Achievement unlocked!!