Back 4 Blood includes a variety of attachments. Attachments can be purchased from a vendor or found throughout the levels.

Attachments can be broken up into seven categories called "Optics", "Barrels", "Magazines", and "Stocks" for Firearms. For Melee weapons and the Bow the melee attachment categories are "Materials", "Grips", and "Handguards". Each having their own rarity of Broken, Uncommon, Rare, Epic, and Legendary.

Weapons found during a level have a chance of being pre-equipped with any amount of the attachments listed here. They can also have "faults", displayed as red (Broken) attachments, which decrease the efficiency of the weapon. Starting into later parts of an Act will spawn weapons with any amount of attachments listed here.

Patch 1.13 introduces attachments for melee weapons and the Bow.

NOTE: Both the Belgian and 357 Magnum cannot equip any Extended Mags, however can be found using Short Mags.

Firearms Attachments[]

Barrels[]

Barrel Attachments[]

Compensator	Uncommon	Rare	Epic
	+ 20% Recoil Control + 15% Move Speed While Firing	+ 40% Recoil Control + 30% Move Speed While Firing	+ 60% Recoil Control + 45% Move Speed While Firing

Laser Sight	Uncommon	Rare	Epic
	+ 10% Accuracy	+ 20% Accuracy	+ 30% Accuracy

Long Barrel	Uncommon	Rare	Epic
	+ 25% Effective Range	+ 50% Effective Range	+ 75% Effective Range

Suppressor	Uncommon	Rare	Epic
	Reduces distances that enemies react to gunfire by 50%. Increases damage dealt to unaware enemies by 25%.	Reduces distances that enemies react to gunfire by 75%. Increases damage dealt to unaware enemies by 50%.	Reduces distances that enemies react to gunfire by 100%. Increases damage dealt to unaware enemies by 75%.

Broken Barrel Attachments[]

Bent Barrel	Broken
	-30% Accuracy

Warped Barrel	Broken
	-60% Recoil Control

Legendary Barrel Attachments[]

All Bite	Rare	Legendary
	+20% Bullet Damage -30% Effective Range DISABLES: Bullet Penetration	+30% Bullet Damage DISABLES: Bullet Penetration

Laser /Compensator	Legendary
	+ 40% Recoil Control + 30% Move Speed While Firing + 20% Accuracy

Spray 'n Pray	Rare	Legendary
	Infinite Effective Range - 50% Accuracy	Infinite Effective Range

	Rare	Legendary
	+ 80% Recoil Control - 60% Move Speed while firing	+ 100% Recoil Control

Magazines[]

Magazine attachments[]

+P Ammo	Uncommon	Rare	Epic
	+ 5% Bullet Damage	+ 10% Bullet Damage	+ 15% Bullet Damage

AP Ammo	Uncommon	Rare	Epic
	+ 50% Bullet Penetration	+ 75% Bullet Penetration	+ 100% Bullet Penetration

Extended Mag	Uncommon	Rare	Epic
	+ 25% Magazine Size	+ 50% Magazine Size	+ 75% Magazine Size

Fast Mag	Uncommon	Rare	Epic
	+ 20% Reload Speed	+ 30% Reload Speed	+ 40% Reload Speed

HP Ammo	Uncommon	Rare	Epic
	+ 25% Bullet Stumble	+ 50% Bullet Stumble	+ 75% Bullet Stumble

Broken Magazine Attachments[]

Corroded Mag	Broken
	- 5% Bullet Damage

Short Mag	Broken
	- 25% Magazine Size

Sticky Mag	Broken
	- 20% Reload Speed

Legendary Magazine Attachments[]

Can of Whup-Ass	Rare	Legendary
	+20% Fire Rate +75%Magazine Size -40% Recoil Control	+20% Fire Rate +75%Magazine Size

Extended +P Mag	Legendary
	Firepower +10% + 50% Magazine Size + 10% Bullet Damage

Extended AP Mag	Legendary
	Firepower +10% + 50% Magazine Size + 100% Bullet Penetration

Extended Fast Mag	Legendary
	Firepower +10% + 50% Magazine Size + 30% Reload Speed

Extended HP Mag	Legendary
	Firepower +10% + 50% Magazine Size + 50% Bullet Stumble

Fast +P Mag	Legendary
	Firepower +10% + 30% Reload Speed + 10% Bullet Damage

Fast AP Mag	Legendary
	Firepower +10% + 30% Reload Speed + 100% Bullet Penetration

Fast HP Mag	Legendary
	Firepower +10% + 30% Reload Speed + 50% Bullet Stumble

Less is More	Rare	Legendary
	+ 50% Bullet Damage - 20% Fire Rate - 30% Magazine Size	+ 50% Bullet Damage - 20% Fire Rate

The Motherload	Rare	Legendary
	+ 125% Magazine Size - 30% Reload Speed	+ 200% Magazine Size

Optics[]

Optics Attachments[]

ACOG	Uncommon	Rare	Epic
	2x Magnification + 5% Weakspot Damage	2x Magnification + 10% Weakspot Damage	2x Magnification + 15% Weakspot Damage

High Zoom Scope	Uncommon	Rare	Epic
	4x Magnification + 5% Weakspot Damage	4x Magnification + 10% Weakspot Damage	4x Magnification + 15% Weakspot Damage

Holo-Sight	Uncommon	Rare	Epic
	10% Move Speed while aiming down sights	20% Move Speed while aiming down sights	30% Move Speed while aiming down sights

Reflex Sight	Uncommon	Rare	Epic
	10% Move Speed while aiming down sights	20% Move Speed while aiming down sights	30% Move Speed while aiming down sights

Broken Optic Attachments[]

Heavy Reflex Sight	Broken
	-30% ADS Speed

Legendary Optic Attachments[]

Needle's Eye	Rare	Legendary
	Gain +5% Bullet Damage for each Weakspot kill in the last 10 seconds -50% ADS Speed	Gain +5% Bullet Damage for each Weakspot kill in the last 10 seconds

Sharpshooter's Monocle	Rare	Legendary
	2x Magnification + 100% Weakspot Damage - 25% Bullet Damage	2x Magnification + 100% Weakspot Damage

Staring Contest	Rare	Legendary
	4x Magnification - 25% Bullet Stumble Damage The first shot against any ridden stumbles it (This effect can only occur once per ridden)	4x Magnification The first shot against any ridden stumbles it (This effect can only occur once per ridden)

Wandering Eye	Rare	Legendary
	+ 60% ADS Speed + 75% Move Speed while firing - 15% Weakspot Damage	+ 75% ADS Speed + 100% Move Speed while firing

Stocks[]

Stock Attachments[]

Competition Stock	Uncommon	Rare	Epic
	+ 20% ADS Speed	+ 30% ADS Speed	+ 40% ADS Speed

Lightweight Stock	Uncommon	Rare	Epic
	+ 5% Move Speed + 5% Sprint Speed	+ 7.5% Move Speed + 7.5% Sprint Speed	+ 10% Move Speed + 10% Sprint Speed

Tactical Stock	Uncommon	Rare	Epic
	+ 50% Swap Speed	+ 75% Swap Speed	+ 100% Swap Speed

Broken Stock Attachments[]

Bulky Stock	Broken
	-25% Swap Speed

Heavy Stock	Broken
	-10% Move Speed

Legendary Stock Attachments[]

Go-Getter	Rare	Legendary
	Spread is no longer increased by movement	Spread is no longer increased by movement +20% Accuracy

Light Competition Stock	Legendary
	+ 30% ADS Speed + 10% Move Speed

Light Tactical Stock	Legendary
	+ 75% Swap Speed + 10% Move Speed

Steady Hand	Rare	Legendary
	While crouching, gain + 40% Accuracy	While crouching, gain + 70% Accuracy

Walking Stick	Rare	Legendary
	+20% Move Speed DISABLES: Sprint	+30% Move Speed DISABLES: Sprint

Melee Attachments[]

Melee attachments can be used on all melee weapons as well as the Bow.

Materials[]

Materials Attachments[]

Aluminium Core	Uncommon	Rare	Epic
	Handling +5% + 10% Melee Stamina Efficiency + 10% Bow Stamina Efficiency	Handling +10% + 20% Melee Stamina Efficiency + 20% Bow Stamina Efficiency	Handling +16% + 30% Melee Stamina Efficiency + 30% Bow Stamina Efficiency

Resonant Metals	Uncommon	Rare	Epic
	Melee and Bow kills heal 1 health.	Melee and Bow kills heal 2 health.	Melee and Bow kills heal 3 health.

Steel Reinforcement	Uncommon	Rare	Epic
	+ 7% Damage Resistance	+ 10% Damage Resistance	+ 13% Damage Resistance

Legendary Material Attachment(s)[]

The Second Coming	Rare	Legendary
	Become invulnerable for 8 seconds upon death or incap. Each melee or bow hit restores 1 health and 0.5 trauma for the duration of the invulnerability. This effect can only occur once per level.	Become invulnerable for 10 seconds upon death or incap. Each melee or bow hit restores 2 health and 1 trauma for the duration of the invulnerability. This effect can only occur once per level.

Grips[]

Grip attachments[]

Compact Redesign	Uncommon	Rare	Epic
	Mobility +5% + 5% Move Speed + 5% Sprint Speed	Mobility +8% + 7.5% Move Speed + 7.5% Sprint Speed	Mobility +10% + 10% Move Speed + 10% Sprint Speed

Quickdraw Lanyard	Uncommon	Rare	Epic
	Handling +10% + 50% Swap Speed	Handling +16% + 75% Swap Speed	Handling +20% + 100% Swap Speed

Tactical Grip	Uncommon	Rare	Epic
	Firepower +10% + 10% Melee Attack Speed + 10% Bow Attack Speed	Firepower +16% + 15% Melee Attack Speed + 15% Bow Attack Speed	Firepower +20% + 20% Melee Attack Speed + 20% Bow Attack Speed

Legendary Grip Attachment(s)[]

The Apocalypse	Rare	Legendary
	Increase the damage of heavy attacks and arrows fired in ADS by 0.75% per point of stamina spent on the attack. Recover 100% of the stamina spent if an enemy is killed by the attack. Heavy attacks and arrows fired in ADS consume all of your remaining stamina.	Increase the damage of heavy attacks and arrows fired in ADS by 1.25% per point of stamina spent on the attack. Recover 100% of the stamina spent if an enemy is killed by the attack. Heavy attacks and arrows fired in ADS consume all of your remaining stamina.

Handguards[]

Handguard attachments[]

Extended Handle	Uncommon	Rare	Epic
	Range +10% + 10% Melee Attack Range + 20% Arrow Speed	Range +16% + 15% Melee Attack Range + 30% Arrow Speed	Range +20% + 20% Melee Attack Range + 40% Arrow Speed

Lead Counterweight	Uncommon	Rare	Epic
	Firepower +5% + 25% Stumble Damage	Firepower +10% + 50% Stumble Damage	Firepower +16% + 75% Stumble Damage

Titanium Spikes	Uncommon	Rare	Epic
	Firepower +10% + 10% Damage	Firepower +16% + 15% Damage	Firepower +20% + 20% Damage

Legendary Handguard Attachment(s)[]

The Grim Reaper	Rare	Legendary
	Gain 5% instant kill chance, increasing by 0.15% with each melee or bow kill. When an instant kill occurs, restore 2 health.	Gain 10% instant kill chance, increasing by 0.15% with each melee or bow kill. When an instant kill occurs, restore 3 health.