Alternate Fire modes (or alt-fire modes) are unique methods of attack featured on many weapons in Borderlands 3.
Atlas weapons shoot a tracking round. After applying the round to an enemy, all regular shots will target the tracked enemy for a time dependent on the nature of tracking round fired; the general rule is if the tracking round on the weapon is capable of tagging multiple enemies at once, then the tracking duration will be shorter. Tracking rounds automatically replenish their on-weapon stock after a few seconds, with some options needing longer to regenerate.
There are different types of tracking rounds:
- Tracker Dart: A singular dart is shot which can track one enemy.
- Tracker Burst: A small number of darts are shot in a shotgun-like burst. It is possible to track multiple targets if the darts connect with more than one enemy.
- Tracker Puck: A magnetic puck that sticks to the enemy it's shot at. Upon the target's death, it will drop off and has a chance to seek out a new target within a small radius. The puck's tagging effect lasts for eighteen seconds.
- Tracker Grenade: A grenade-like charge that is shot in an arc, and will rise up on impact with terrain and explode into hundreds of darts that will track all enemies within the burst radius. The grenade can prematurely explode on directly impacting an enemy. The grenade's tagging effect lasts for twelve seconds.
Dahl weapons switch between two different firing modes. This will change the behavior of the gun as well as the sight's zoom.
Of the following, two are available per weapon:
- Semi-Auto: Single shots; usually combined with a stronger zoom; increased damage (except for pistols)
- Burst Fire: A burst of typically around 3-5 bullets
- Full-Auto: Holding down the trigger will fire continuously; usually has the weaker zoom
Maliwan weapons can switch between two different Elemental Damage types.
Torgue weapons can switch between their regular explosive projectiles and sticky explosives. Once stuck, these sticky bombs will rapidly explode in sequence of impact when the weapon is reloaded, the mode is switched or the character switches to another weapon. Each successive stuck projectile will do more damage depending on how many rounds detonated before it, for possibly extraordinary amounts of single-target damage.
Vladof weapons have various underbarrel attachments that offer a different way of dealing damage. On assault and sniper rifles, switching modes is represented by rotating the barrel so that the currently active option is on top - with exception of the bipod and secondary chain gun barrel attachments. Vladof underbarrel attachments include:
- Taser: Tasers fire in a slight arc and will continuously deal damage to both enemies directly hit and enemies around the taser itself, which means even missed tasers can still do damage if the user can keep enemies in the taser's vicinity. Uses ammunition from the character's ammo reserve rather than the current magazine, and regenerates itself after a few seconds.
- Zip Rockets: Fires tiny rockets in a straight line. It has its own magazine which will regenerate after a short time.
- Second Barrel: A secondary barrel below the regular one. The barrels rotate after every shot, increasing the fire rate of the weapon.
- Grenade Launcher: Does not draw from the current magazine and has a varying maximum of grenades that can be launched at one time. Regenerates one grenade at a time.
- Secondary Chain Gun Barrel: A weapon with a chain gun barrel can have a secondary one as an attachment. By default, only the upper one is active. When toggled, they will rotate by 90°, activating them both for increased fire rate. Ammo consumption and recoil will increase with the fire rate as well.
Assault Rifles/Sniper Rifles:
- Bipod: Switching modes deploys a bipod that drastically improves Handling and Accuracy, but reduces movement and aim speed.
- Shotgun: Possesses variable projectile counts and pellet damage statistics, and like the grenade launcher attachment, the weapon regenerates one shotgun round at a time separate from the main magazine but will draw each round from the user's current ammo reserves. Each shot of the shotgun will take one bullet.
- Rockets: Similar to the Assault Rifle's Grenade Launcher, this attachment grants additional explosive projectiles. The amount of Rockets can vary.
- Micro-Rockets: This alters the method of projectile delivery, rather than being an alternate weapon attached and draws from the current magazine of the weapon. Fires a swarm of smaller missiles to bombard an area instead of a single large rocket.
- Big-Boy Rocket: The damage dealt by this single rocket is at least double, and sometimes triple that of the normal rocket fired. Regenerates its round relatively slowly, but does draw from reserve ammo pool and not the current magazine.
- Mortar: Designed to assault enemies behind cover. Regenerates its round relatively slowly, but does draw from reserve ammo pool and not the current magazine.
- Unique and legendary weapons can differ from their manufacturer's regular Alternative Fire Mode in various ways. Examples include:
- The Vortex Grenade utilized by Ruby's Wrath is a variant of the Atlas Tracker Grenade. It is fired at a noticeably higher velocity and will bounce forward instead of stopping on the first impact with terrain. When it explodes, however, it creates an effect identical to a singularity grenade in addition to tracking all enemies in range. The grenade's tagging effect lasts for eight seconds and it has a cooldown duration of 12 seconds.
- The Malak's Bane and ASMD switch between different projectiles.
- The Cloud Kill, Krakatoa, Tigg's Boom, Moonfire and Bearcat have no alt-fire mode.
- The Hornet has fixed burst fire and only toggles zoom magnification on mode switch. A similar feature is also present on the Hellfire, Crader's EM-P5 and Good Juju.
- The Brashi's Dedication switches between shock and corrosive.
- The Freeman's fired rockets are laser-guided and will move to wherever the cursor points to and lacks the conventional tracking feature of most Atlas Launchers. It has no alt-fire mode as a result.
- The Vosk's Deathgrip alt-fire shoots a puck that creates a singularity.
- Switching Fire Modes takes a little bit of time. Mode Switch Speed is affected by the same modifier as Weapon Switch Speed.