40mm Smoke Grenade

A hand-thrown smoke grenade covers you. This one covers the spot you need to reach. Fired from the multiple grenade launcher, it drops a wall of smoke between you and a sniper on a distant ridge, which no throwing arm can reach.

The situation it was made for: your teammate is knocked in the open, someone is holding the angle from a hill, and running out there means two bodies instead of one. Put smoke between the hill and the downed player, then go. The same trick works for crossing a field during an online raid or pulling loot out of a crate while another group watches.

Smoke does nothing on its own, so it pays to carry it alongside HE grenades. Blind the roof, switch ammo, then punish whoever stays up there.

You can't craft or research it, so what you shoot comes off heavy scientists at oil rigs and Bradley. If the same run drops 40mm shotgun rounds, keep them for the moment someone pushes into close range.