40mm Smoke ammunition is designed for use with a grenade launcher. On impact, it creates a thick gray/white cloud of smoke.
Battlefield: Bad Company 2
— In-game description
The 40mm Smoke Launcher is a gadget available for the Assault kit in Battlefield: Bad Company 2 that allows the player to fire smoke grenades from a 40mm under-barrel grenade launcher. Once the smoke grenade impacts anything, it will create a large cloud of sight obstructing smoke that will slowly dissipate after a few moments. The smoke makes it very difficult to see anything inside or beyond it, so covering objectives or sightlines with smoke can make them easier to capture or cross. Something to take into account, however, is that 3D spotted enemies will have a spotted marker over them in the smoke, so its advisable to avoid being spotted before crossing through it.
Like the standard 40mm Grenade, if the a player hits another player (enemy on core, anyone on Hardcore) directly with the smoke grenade, the other player will be instantly killed, which can make the grenade a rather lethal impromptu weapon if the player is caught by surprise. Another use for the smoke is that it has the ability to disable and remove tracer darts.
— Battlelog description
The M320 Smoke is a variant of the M320 grenade launcher that fires smoke grenades. It is the final unlockable ammunition for the grenade launcher. When fired, the projectile arcs just as the 40mm grenade proper does, and on contact immediately produces a large, opaque cloud of smoke over an area of several meters in any given direction from the epicenter of the impact. Those caught within suffer reduced vision, but can still make out players that are within a few meters.
Although smoke grenades inflict no splash damage, the projectile can be fatal to infantry at any range. Offsetting this power is the grenade's relatively slow velocity.
On Normal and Custom games where 3D spotting is enabled, players can still see enemy namecards if they are in the player's crosshairs, potentially making the smoke worthless, especially if fired at one's own feet.
— Battlelog description
40mm Smoke returns in Battlefield 4 as usable ammunition for the M320. It functions similarly to its Battlefield 3 counterpart, but covers a much smaller area compared to the also available M18 Smoke Grenade. The 40mm Smoke's main advantage over the M18 is that it is able to provide immediate, albeit smaller, coverage of an area, as the M18 requires a few seconds for the smoke to plume fully. Like its past counterparts, the 40mm Smoke is able to kill a player with a direct impact, though players running the ARMOR specialization will take two hits unless they're already low on health or are hit in the head by the grenade.
Unlike its iteration in Bad Company 2 and Battlefield 3, the smoke produced by the grenade now obscures the player's hands and weapon while in the smoke, as well as blocking any Spotted players while looking through it, making it much more difficult to navigate and attack through the smoke.
- In Battlefield: Bad Company 2, the icon for 40mm Smoke Launcher is a GP-25/GP-30, although using this gadget does not change the in-game launcher.
- Weapon stars are not awarded for kills earned with the smoke launcher.
- In Battlefield 3, there was a glitch where if the player attached the M320 SMOKE to the AUG while equipped with an Underslung rail, the round had very high velocity, giving it the ballistics/bullet drop of an assault rifle bullet, making it extremely deadly. It has since been patched in a hot fix by DICE, making the AUG unable to use the underslung M320 SMOKE.
- Battlelog incorrectly notes that the M320 Smoke fires 40mm buckshot. Its page description also reads, "A close range 40mm buck shot, for those close quarters." Oddly, the pop-up text reads otherwise.