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Borderlands 4 Guide

Borderlands 4 Gearology - Guns & Gear Explained

Late Game
Mechanics
Weapons
Enhancements
Class Mods
Shields
Legendary Loot
Updated on Jan 22, 2026
Jan 22, 2026

Overview

Gearology - Guns & Gear

The Gearology guide is a dedicated place to explain and expose mechanics, formula functionality and any other obscure facts related to specific guns or gear in Borderlands 4.

Not all items in the game will be featured in this. The focus are items that have effects that could use further explaining, that have unexpected mechanics, or ones where learning their formula placement is relevant.

Many thanks to...

Prismatic, for the original Borderlands 3 Gearology guide that inspired this.

JoeForLong, Grace, Lango, Iserrot, Girthquake and wrw713 for their massive contributions to this guide.

What is Soup? On-Shot? On-Hit?

If you're confused by mentions of formula terminology or don't recognize what something means, I recommend checking the relevant guides from the Noteworthy Resources section below.

Noteworthy Resources

Guns

Anarchy Shotgun

Cause I WANNA be!

Mutualism - On Auto-Reload or kill, grants +15% Damage and -15% Accuracy fo a Maximum of 20 Stacks which reset on manual reload.

  • The damage from Mutualism is additive to On-Shot Gun Damage.
  • Underbarrel attachments like Proximity Mines can benefit from Mutualism.
  • Stacks of Mutualism can be gained by reload canceling. An example of this is emptying the mag and interrupting the reload animation through melee attacks until maximum stacks are achieved.

Asher's Rise

How can we possibly have the slightest idea what to expect?

Slow Burn - Critical Hits apply Status Effects instead of increased Impact Damage.

  • The Slow Burn Status Effect is entirely separate from the weapon card's listed Status Effect damage. It applies at 55% effectiveness of the listed weapon card Status Effect.
  • On a hit that applies both the card Status Effect (using Primed Potency Maliwan Enhancement), the Slow Burn status is applied after the weapon card Status Effect, meaning it won't eat up skill triggers like Prismatic Ichor with using its weaker-than-card values.

Boomslang Sniper Rifle

Everything is blooming most recklessly.

Bullet Pollinator - After Reloading, the first Critical Hit Ricochets a Sticky Projectile to up to 3 nearby enemies.

  • The Bullet Pollinator special effect is not triggered by 'mag refills' achieved by Witchy Trigger Finger, Super Soldier or Tier 3 Trickshot.

Bonnie and Clyde Assault Rifle

From a schoolboy to a rattlesnake.

Pair of Thieves - On kill, grants +150% Damage for the Gun's other Mode and refills its magazine.

  • The Pair of Thieves damage boost is additive to On-Shot Gun Damage.
  • Damage boost is lost on manual reload and on emptying the magazine.

G.M.R Assault Rifle

O, inheritor of grace!

Big Name Hunter - When Zoomed in, Damage increases by +100%, Shot Cost increases by +100%, and fire rate decreases by -50%.

  • The Big Name Hunter damage boost is applied on shot, and is additive to On-Shot Gun Damage.
  • Holding down the fire button then ADSing sometimes can result in the gun's normal, non-penalized fire rate carrying over for a few shots.


Golden God Shotgun

I am untethered, and my rage knows no bounds!

Rage - When Overheating, the Bulletforge does not break, but instead continually consumes greater amounts of Ammo.

  • The Rage effect provides 60% On-Shot Gun Damage for every 6 bullets fired while overheating, up to 300%.
  • Each step also increases the ammo consumed. Ammo consumption continues to increase even at max damage bonus.

In more detail, the gun follows the below progression based on the count of "shots fired" when overheating:

Shots Fired

Damage Bonus

Ammo Cost

0 - 5

0%

1

6 - 11

60%

3

12 - 17

120%

4

18 - 23

180%

5

24 - 29

240%

6

30 or more

300%

8 - Continually ramping

Husky Friend Shotgun

We just prefer to use "Husky".

Husky Auto Turret - Underbarrel

  • The Husky Auto Turret underbarrel deals ordnance damage but does not benefit from ordnance damage boosts.

King's Gambit Pistol

The refutation of any gambit begins by accepting it...

Holy Hell - When shot, thrown Gun Ricochets Projectiles to nearby enemies.

  • The Holy Hell thrown gun is a Tediore (Throw on Reload) Combo Orb which can be shot for its special ricochet effect.

Orb Mechanics

Spawns 4 bullets for each projectile it was hit with on during its active frame.

  • The 'bullet spawn' has fire rate of 3 and cannot be increased.
  • Testing results suggest that there is 1 active frame and 19 recovery frames at 60 FPS. It's maybe possible that at 30 FPS one could get longer active frames.

Orb Projectiles Damage

The damage of the spawned projectiles from shooting the orb are based on King's Gambit card damage, not on the weapon the orb was shot with.

  • The projectiles benefit from On-Hit Gun Damage and On-Shot Gun Damage, but do not benefit from some other On-Shot boosts like Amp, Neutron Capture or Piercer Jakobs Enhancement.
  • Rafa They are considered Indirect Projectiles.

Other Notes

  • With Tier 3 High Caliber, sticky projectiles can be shot through the orb.

Rainbow Vomit Shotgun

I think I'm gonna...

Color Spray - Shoots Element A, Element B, and Element C droplets.

  • Shoots two droplets of each element, for a total of six projectiles.
  • Each droplet spawns a Splat under the enemy, dealing x0.25 Card Damage per tick for 13 ticks over 3s.
  • The Splats can cause status effects. These work normally and are considered statuses for skills like Prismatic Ichor, Neutron Decay and Inspirado.

Splat damage is not considered Hazard damage.

  • Benefits from Amp and Enhancement On-Shot boosts.
  • Benefits from Elemental and Splash On-Hit boosts.

Stop Gap Sniper Rifle

Do better. Try harder.

Reconfigure - When firing, Fire Rate decreases down to 20%, but damage inreases up to 750%.

  • The Reconfigure damage boost is a 7.5x multiplier when fully ramped. It is a pure multiplier.

San Saba Songbird Pistol

Let me tell you, buddy - there's a faster gun...

Dueling Pistol - Deals +100% Damage for 5s after swapping guns

  • The Dueling Pistol damage boost is additive to On-Shot Gun Damage.
  • The damage boost works on Tediore (Throw on Reload) explosions, and also on the gunshots from the 'Shooting' reload variants.

Vamoose Sniper Rifle

Faster than a knife fight in a phone booth.

Scare

  • Dumps the entire mag when fired, capped to 10 shots, even if using infinite ammo effects or magazine size increases.

Zipper Pistol

Who's the shot caller now?

Prison Rules - Gain +75% Critical Damage and +75% Damage when hitting a target in the back.

  • The angle for activation of Prison Rules seems to be a 150° cone behind the target.
  • The +75% Critical Damage is additive to Gear Crit.
  • The +75% Damage is additive to On-Shot Gun Damage.

Class Mods

Amon Class Mods

Lamplighter

No need of sun to light the way.

Special Effect - Whenever Amon Critically Hits with Guns, he restores 1.5% Action Skill Duration. While Action Skill is active, he gains 1.4% On-Hit Gun Damage and 2% Melee Damage every second until Action Skill ends.

  • The in-game description omits the numerical values.

Harlowe Class Mods

Bio-Robot

This place is not a place of honor.

Special Effect - Entanglement creates alternating Cryo hazard & Radiation hazards.

  • Hazards don't spawn under flying enemies, and don't appear to have any vertical range.
  • If they don't touch it, it does nothing.

Generator

Every lie we tell incurs a debt to the truth.

Special Effect - Whenever Harlowe activates her Flux Generator, she decreases her remaining Action Skill Duration by 50% and gains 200% Action Skill Power.

  • Does not apply any boost at initial Action Skill deployment. Every redeployment after that receives the +200% boost, capped at 10.
  • Works with Group Study, but only boosts Nuclear Winter when applied to Group Study.

Trooper

I'm doing my part!

Special Effect - Critical hits with Guns partially restore 4% of Ordnance Cooldown. On Ordnance Activation, gain 50% On-Hit Gun Damage and 50% Action Skill Damage for a 8s.

  • The in-game description omits the numerical values.

Rafa Class Mods

Dancer

Ya está vencido.

Special Effect - Overdrive bonuses are increased by +100%. Overdrive ends whenever Rafa's Action Skill ends.

  • Actually doubles all Overdrive bonuses after Soltado and Jaque, which are additive with each other.

Vex Class Mods

Avatar

I'm the Avatar. You Gotta Deal With it!

Special Effect - Vex and her Minions gain 20% increased Damage Dealt for each active Attunement Skill. Each active Attunement Skill also grants Vex and her Minions 30% Damage Reduction against its matching Elemental Type.

  • The in-game description omits the numerical values.

Illusionist

Are you watching closely?

Special Effect - Specters and Reapers have a chance to be Badasses, gaining 25% increased Maximum Health and 50% Damage Dealt. This chance increases the longer it hasn't occurred and will at least occur once every 70 seconds.

  • The in-game description omits the numerical values, and wrongly displays the guaranteed Badass cooldown as 90 seconds.

Kindread Spirits

You'd think they'd never seen a girl and a cat on a broom before.

Special Effect - Using a Command Skill grants Vex 30% Bonus Kinetic Minion Damage with Guns for a 10s Duration. Command Skills deal Gun Damage in addition to its other types.

  • The in-game description omits the numerical values.

The Special Effect essentially makes Command Skills into On-Hit Gun Damage sources, meaning they can trigger gun-based skills like Deadwire and benefit fully from On-Hit Gun Damage boosts.

  • This also works on Trouble Bubble, even though it is not a Command Skill.

Misericorde

May the knife chip and shatter.

Special Effect - Phase Daggers gain a chance to Ricochet. Critical Hits grant a stack of Misery for a 20s duration, granting 1.4% Skill Damage. Misery can stack up to 50 times.

  • The in-game description omits the numerical values.
  • Currently, Phase Dagger skills are Haruspex, Pincushion and Vorpal Fang.
  • Phase Dagger critical hits don't stack Misery. You read that right.


Shields

Super Soldier

I'll never forget the adventures we had.

Power Play - When Energy Shield fills, grants an Overshield equal to 35% of Shield's Card Capacity. When Energy Shield is full, grants +25% Fire Rate, +25% Movement Speed, and regens 1 Ammo/s.

Ammo Regen Mechanics

  • Regenerates ammo of the primary fire for a gun while swapped into the underbarrel. Consequently, will not regen underbarrel ammo.
  • Does not regenerate ammo of the other gun type for Daedalus or Daedalus (Underbarrel/Multi-Loader) guns, but will regen either primary or secondary ammo type when active.
  • Does not regenerate reserve ammo, only missing ammo from a magazine.
  • Regenerates up to full ammo reserves for COV (Unlimited Mag) guns.

Enhancements

Transfuser

Video Explanation by Girthquake

Transfuser Remembers the most recent DOT it transferred. If you change elements will actually apply that DOT to your new one as well.

  • If you transfer a Corrosive DOT then switch to Shock - you get a Corrosive AND a Shock DOT.
  • If you use a weapon that only has one element it will double that DOT on transfer.

If you set the DOT element, then switch to a gun that does not have that element it will use the DOT value on the card of the element that's not in use.

  • Example: if you prime a Fire DOT, swap to a Corrosive/Shock gun, then apply a Corrosive DOT that gets transferred - a Fire DOT will also be applied. That Fire DOT will use the Shock mode's listed DOT value.

The spread DOT gets On-Shot bonuses. It does not retain Amp.

  • Swapping back to a single element weapon and transferring that DOT will get you back to double DOTs in one element.

Persists until save quit (Fast Travel not tested).

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