13.1" First Responder

"Custom barrel with a slight length increase and polygonal rifling for increased muzzle velocity and improved range. Adds little additional weight."

— In-game description

The 13.1" First Responder is a barrel attachment featured in Call of Duty: Modern Warfare and Call of Duty: Warzone. It is uniquely available to the Uzi submachine gun.

v • d • e Weapons of Call of Duty: Modern Warfare

Assault Rifles	Kilo 141 · FAL · M4A1 · FR 5.56 · Oden · M13 · FN Scar 17 · AK-47 · RAM-7 (Season 1) · Grau 5.56 (Season 2) · CR-56 AMAX (Season 4) · AN-94 (Season 5) · AS VAL (Season 6) AK-12 (SP)

Submachine Guns	AUG · P90 · MP5 · Uzi · PP19 Bizon · MP7 · Striker 45 (Season 2) · Fennec (Season 4) · ISO (Season 5) · CX-9 (8/3/21 Update)

Shotguns	Model 680 · DP-12/R9-0 Shotgun · 725 · Origin 12 Shotgun · VLK Rogue (Season 2) · JAK-12 (Season 6)

Light Machine Guns	PKM · SA87 · M91 · MG34 · Holger-26 (Season 1) · Bruen Mk9 (Season 3) · FiNN LMG (Season 5) · RAAL MG (8/24/21 Update)

Marksman Rifles	EBR-14 · MK2 Carbine · Kar98k · Crossbow (Season 1) · SKS (Season 3) · SP-R 208 (Season 6)

Sniper Rifles	Dragunov · HDR · AX-50 · Rytec AMR (Season 4)

Handguns	X16 · 1911 · .357 · M19 · .50 GS · Renetti (Season 3) · Sykov (4/15/21 Update)

Launchers	PILA · Strela-P · JOKR · RPG-7 MGL-32 Grenade Launcher (SP/SO/WZ)

Melee	Primary: Riot Shield Secondary: Combat Knife · Kali Sticks (Season 4) · Dual Kodachis (Season 5)

Special	Minigun

Attachments	Muzzle: Flash/Suppressor: Flash Guard · Lightweight Suppressor · Tactical Suppressor · Monolithic Suppressor · Colossus Suppressor · ZLR Sabre · FORGE TAC Marauder · Oil Can Suppressor · RAAL Monocore · Rytec AMR Suppressor Brake/Comp: Muzzle Brake · AN-94 Sonic Brake · XRK Tank Brake · Compensator · Desperado Pro Compensator Misc: Choke · Bayonet · Breacher Device · CQB Breacher Device Barrel: Kilo 141 (Singuard Arms 16.6" SOCOM · Singuard Arms 19.8" Prowler · Singuard Arms Whisper) · FAL (18.0" Ultralight · XRK Marksman · 13.0" OSW Para) · M4A1 (FSS 11.5" Commando · Stock M16 Grenadier · FSS 14.5" Tac Lite · Corvus Custom Marksman · FSS 12.4" Predator) · FR 5.56 (FR 15.9" Commando · FR 24.4" Sniper · FORGE TAC Ultralight) · Oden (Oden Factory 810mm · Oden Factory 730mm · Oden Factory 420mm) · M13 (Tempus Mini · Tempus Cyclone · Tempus Marksman) · FN Scar 17 (FORGE TAC 17.2" LB · FORGE TAC 20.0" LB · FORGE TAC CQC Pro) · AK-47 (Spetsnaz Elite · 23.0" RPK Barrel · 8.1" Compact Barrel · 23.0" Romanian) · RAM-7 (FTAC 13.5" Compact · FORGE TAC Eclipse · FSS Ranger) · Grau 5.56 (ZLR Drifter A-08 · Tempus 26.4" Archangel · XRK CZEN mk2 · FSS 20.8" Nexus · FSS 11.8" Squall) · CR-56 AMAX (FSS 8.3" Intruder · XRK Zodiac S440 · FSS 11.8" Squall) · AN-94 (AN-94 Factory 330mm · AN-94 Factory X-438mm · VLK AN-94 Sila) · AS VAL (VLK 105mm Sova · Stovl SOF · VLK 200mm Osa) · AUG (407mm Extended Barrel · 407mm Lightweight · 622mm Long Barrel) · P90 (FORGE TAC Retribution · FSS 10.6" Pro) · MP5 (FSS Light · Monolithic Integral Suppressor · FSS Mini · Subsonic Integral Suppressor) · Uzi (13.1" First Responder · 8.5" Factory Mini · 16.5" Factory Carbine · FSS Carbine Pro) · PP19 Bizon (8.7" Steel · 8.7" Polygonal · 8.7" Aluminum) · MP7 (FSS STRIKE · FSS RECON · FSS SWAT) · Striker 45 (300mm Poly Barrel · 400mm Stainless Steel · 150mm Stainless Steel) · Fennec (ZLR 16" Apex · ZLR 18" Deadfall) · ISO (FTAC 225mm Dominator · FSS Revolution · ISO 140mm CQB · FSS Nightshade) · CX-9 (CX-38E · CX-23S · CX-23 · CX-38 · CX-38S) · Model 680 (XRK 18.0" Liberator · XRK 14.0" SWAT · XRK 30.0" Sport) · R9-0 Shotgun (FORGE TAC Sentry · FORGE TAC Gemini) · 725 (Tempus Smooth Bore · Sawed-off Barrel · Tempus 32" Competition) · Origin 12 Shotgun (FORGE TAC Precision · FORGE TAC Wideshot · FORGE TAC Impaler) · VLK Rogue (VLK Czar · 6" Revolt · 16" Warlord) · JAK-12 (ZLR J-2800 Influx · JAK Urban King · ZLR J-3600 Torrent) · PKM (18.2" Compact Barrel · 26.9" Extended Barrel · 25.9" Heavy Barrel) · SA87 (SA87 18.2" Factory · SA87 25.4" Factory · SA87 12.4" Factory) · M91 (M91 Special Forces · M91 Infantry · M91 Heavy) · MG34 (FSS Brute · FSS Stubby · FSS Elite) · Holger-26 (XRK Ultralight · FTAC 8.98" Spitfire) · Bruen Mk9 (XRK Horizon 23.0" · XRK Summit 26.8" · Bruen 18.0" Para) · FiNN LMG (XRK Pro Twist · Factory Adverse · XRK LongShot Advantage · XRK Pro Twist Adverse · FTAC VC-8 Harrier · XRK LongShot Adverse · FTAC VC-8 Harrier Adverse) · RAAL MG (26.0" RAAL ArcForge · 32.0" RAAL Line Breaker · 25.0" RAAL Tri-fold Lite) · EBR-14 (FORGE TAC Precision 20.0" · FORGE TAC Elite · FORGE TAC Precision 22.0") · MK2 Carbine (FSS 18.0" Factory · FSS 20.0" Factory · FSS 24.0" Factory) · Kar98k (Singuard Custom 25.1" · Singuard Custom 21.2" · Singuard Custom 27.6") · SKS (FTAC Landmark · 16" FSS Para · 22" FSS M59/66) · SP-R 208 (ZLR VeraTwist 9.6 · ZLR Asp · SP-R 26" · XRK 208 Dragoon) · Dragunov (510mm Compact Barrel · 660mm Extended Barrel) · HDR (26.9" HDR Pro · 26.0" Bull Barrel · 17.2" Bull Barrel) · AX-50 (Singuard Arms Pro · 17.0" Factory Barrel · 32.0" Factory Barrel) · Rytec AMR (FTAC Seven Straight · FTAC 448mm Dictator · XRK Harbinger) · X16 (Singuard Arms Featherweight · Vanguard Elite · Singuard Arms Advantage) · 1911 (.45 Compact · .45 Match Grade · 1911 Stalker) · .357 (.357 Snub Nose · Silverfield Ordnance .357 · .357 Long) · M19 (XRK L Super · XRK V Extended · A9-16 Lightweight) · .50 GS (FORGE TAC Extended · FORGE TAC Enforcer) · Renetti (Mk1 Competition · Mk1 Extended · Mk3 Burst Mod) · Sykov (SSB 105mm · SSL 308mm · Sorokin 140mm Auto) Cable: 16-Strand Cable · 28-Strand Cable Arms: XRK Thunder 200 Lb · XRK Quill 100 Lb · XRK Carbon Elite Laser: 1mW Laser · 5mW Laser · Tac Laser Optic: Reflex: G.I. Mini Reflex · Solozero Optics Mini Reflex · Cronen LP945 Mini Reflex · Operator Reflex Sight · Aim-Op Reflex Sight · Viper Reflex Sight · Monocle Reflex Sight · Cronen C480 Pro Optic · Corp Combat Holo Sight · APX5 Holographic Sight · PBX Holo 7 Sight · FSS Ring Sight · FSS Integral Reflex Low power: VLK 2.5x Optic · VLK 3.0x Optic · Scout Combat Optic · Integral 2.8x Optic · Cronen 2x2 Elite · Solozero K498 4.0x Integral · Integral Hybrid · Canted Hybrid · 4.0 Flip Hybrid High power: Lockwood Pistol Scope · XRK 4.0x Pistol Scope · XRK MidTrak 4.0x Scope · Brownlee 32mm Scope · Solozero SP-R 28mm · PU Scope · Sniper Scope · Dragunov Scope · XRK Rangemaster VZ · Variable Zoom Scope NV/Thermal: Solozero NVG Enhanced · Merc Thermal Optic · POS-M3 Thermal Scope · Thermal Hybrid · Thermal Sniper Scope · Thermal Dual Power Scope Pumps: FSS R9-0 Bulldog · FTAC Ultralight Pump · FTAC Close Quarters Pro Pump Grip: XRK Race Grip · VLK Prime Pump Grip · XRK ReliaGrip Stock: Various (FORGE TAC Ultralight · FORGE TAC CQS · FORGE TAC Ballast Pack · FORGE TAC CQB Comb · FORGE TAC Stalker · FTAC Stalker-Scout · FTAC Hunter · FTAC Hunter-Scout · FTAC Collapsible · FSS Close Quarters Stock · FSS Heavy Stock Pro · Skeleton Stock · Folded Stock · No Stock · Sawed-off Stock) Kilo 141 only (Singuard Arms Sniper Pro) · FAL (Factory 18" Aluminum Stock) · M4A1 (M-16 Stock · Singuard Arms Invader) · FR 5.56 (FR Ultralight Hollow · FSS Tac-Wrap) · Oden (Oden Ultralight Hollow · FTAC XL Elite Comb) · M13 (M13 Skeleton Stock) · FN Scar 17 (XRK Obelisk Pro) · AK-47 (Field LMG Stock) · RAM-7 (FTAC Equilibrium · XRK Ultralight Hollow · XRK Close Quarters Stock) · Grau 5.56 (FSS Blackjack · XRK StrikeLite III) · CR-56 AMAX (FTAC Spartan · XRK Gatekeeper · CR-56 EXO) · AN-94 (AN-94 Factory Heavy · VLK PX-9 Pero) · AS VAL (VLK Vintazh · FSS Intl. Gen 4 GRU · Stovl 6P30 Skelet · VLK Strelok) · AUG (FTAC Ultralight Hollow) · P90 (Fly Strap) · MP5 (Classic Straight-line Stock) · Uzi (Standard-Issue Wood Stock) · PP19 Bizon (Factory Aluminum Stock · Corvus Skeleton Stock) · Striker 45 (FSS Guardian · FTAC Precision Fixed Stock · XRK Gen III Survivalist Series) · Fennec (FTAC C6 Carbine PRO · ZLR Blade) · ISO (FTAC Vagrant · ISO Collapsible) · CX-9 (CX-MM · CX-FA · CX-FR) · Model 680 (FTAC Stalker-12 · Lockwood Precision Series) · 725 (Cronen Equilibrium · Cronen Pro Light · Tempus Sport) · Origin 12 Shotgun (FORGE TAC Dart) · JAK-12 (ZLR Tsunami · JAK Rabbit Ultralight · FSS Power Wrap) · SA87 (XRK SA87 Heavy Stock Pro · SA87 Ultralight Hollow) · M91 (XRK Striker) · Holger-26 (FSS Ranger · FSS Infantry · XRK Axis) · FiNN LMG (XRK Citadel · XRK M309 Forward Assault · XRK ChainSAW) · RAAL MG (FSS Resistor · FTAC Sandpiper Pro · FTAC Elevate) · EBR-14 (FTAC Precision Comb · FSS Raider Chassis Pro · FTAC Lightweight Stock · FSS Raider Chassis Elite) · MK2 Carbine (Cartridge Sleeve · FSS MK2 Sport Comb · FSS MK2 Precision Comb · MK2 Ultralight Hollow) · Kar98k (STVOL Precision Comb · Hollow Stock Mod · FTAC Sport Comb) · Crossbow (FORGE TAC Apex · FORGE TAC Dart CB · FORGE TAC SpeedTrak) · SKS (SKS Rifle Stock) · SP-R 208 (XRK SP-TAC 208 Ultimate · FSS Virtuoso Pro · XRK SP-LITE 208 Blitz · ZLR SP-R Overseer)· Dragunov (VLK Lightweight Stock) · HDR (FSS Nomad Stock · FTAC Champion) · AX-50 (Singuard Arms Marksman · Singuard Arms Evader · Singuard Arms Assassin) · Rytec AMR (XRK Mastadon · FTAC Trekker · STOVL Tac-Wrap) · Renetti (FTAC SATUS CS-3 · FTAC G-X · FTAC SATUS CS-X) · Sykov (PP-Skelet · PP-Karabin) Rear Grip: Granulated Grip Tape · Rubberized Grip Tape · Stippled Grip Tape Assault Rifles: XRK Void II · Cronen Sniper Elite · FTAC R-89 Rubber · XRK CR-56 Granulated Wrap · XRK CR-56 Stippled Wrap · XRK CR-56 Rubberized Wrap SMGs: FTAC 60 Series Polymer · FTAC G-5 EXO · FTAC 60 Series Rubber · FSS Vice ISO Grip · FTAC Elite ISO Grip · ISO Tac-Form · CX-9 Clutch Grip · CX-9 Ace Grip · CX-9 Tac Grip Handguns: X16 Stock · Lockwood .357 Custom Stock · FSS Raider Stock · XRK Pro Grip · XRK Speed Grip · VLK Spetznaz · VLK Prizrak · VLK Elita Bolt Assembly: Sloan KR-800 DeadEye · Sloan KR-600 Feather Guard: Tempus SlimGrip · FORGE TAC Steady Grip · FORGE TAC Commander Ammunition: Extended Mags · High Capacity Magazines · Drum Magazines · Small Magazine Assault Rifles: 9mm Para 32-Round Mags · 5.45×39mm 30-Round Mags · .300 Blackout 30-Round Mags · M67 10-R Mags · SPP 10-R Mags · .458 SOCOM 10-Round Mags SMGs: 9mm Hollow Point 12-R Mags · 10mm Auto 30-Round Mags · .41 AE 32-Round Mags · .45 Hollow Point 12-R Mags · 5.56 NATO Mags Shotguns: 12 Gauge 6-R Mags · Slug Rounds · Slug 6-R Mags · 8 Round Slug Mags · Dragon's Breath Rounds · Dragon's Breath 6-R Mags · 8-R Dragon's Breath · 8 Round FRAG-12 Mags LMGs: 5.56 CT Belts Marksman/Snipers: .300 Norma Mag 5-R Mags · .338 Lapua Mag 5-R Mags · 25×59mm Explosive 5-R mag · 25×59mm Thermite 5-R mag Handguns: Snake Shot Bolt: FTAC Fury 20" Bolts · FTAC Venom 20" Bolts · FTAC Backburn 20" Bolts Trigger Action: Lightweight Trigger · Heavy Duty Trigger · Match Grade Trigger · Lightweight Single-Action · Heavyweight Double-Action · Lightweight Double-Action Underbarrel: Merc Foregrip · Operator Foregrip · Ranger Foregrip · Commando Foregrip · Tactical Foregrip · Cronen Shark II · Lockwood Precision Series · XRK Truegrip Tactical · Snatch Grip · FFS Clinch · FFS Oblique · PMC Grip · FTAC Speed Grip · XRK Precision Grip · XRK Talon · Bipod · Bipod Foregrip · Granulated Grip Tape · Stippled Grip Tape · Rubberized Grip Tape 40mm High-explosive (M203 · GP25 · FN EGLM) · 40mm Concussive · 40mm Smokescreen · 40mm Recon · 40mm Flash · 40mm Incendiary · 12-Gauge Deputy

Ammunition Types (Warzone)	Heavy Ammo · Light Ammo · Sniper Ammo · Shotgun Ammo · Rockets

Other melee weapons	Fists · Knife · Karambit Knife · Machete · Axe · Bludgeon · Totokia · Cinderblock · Ballistic Knife · Shovel · Sword · Screwdriver · Sickle · Butterfly Knife · Shiv (SP) · Scissors (SP)

Field Upgrades	Munitions Box · Recon Drone · Dead Silence · Stopping Power Rounds · Trophy System · Deployable Cover · Tactical Insertion · EMP Drone · Weapon Drop Cut: Ladder · Ammo Drop · Last Stand

Lethals	Claymore · Frag Grenade · Molotov Cocktail · C4 · Semtex · Throwing Knife · Proximity Mine · Thermite · Rock (SP/WZ)

Tacticals	Flash Grenade · Stun Grenade · Smoke Grenade · Snapshot Grenade · Heartbeat Sensor · Gas Grenade · Stim · Decoy Grenade · Spotter Scope (WZ)

Manufacturers	Corvus Defense · Cronen · FORGE TAC · FSS · Pulse · JAK · Lockwood · Oruzhie · Rothwynn · Silverfield Ordnance · Singuard Arms · Sloan Precision · Solozero · STVOL · Tanto · Tempus Armament · Verdansk Arms Plant · VLK · XRK · ZLR Others: Dynamics Arms Corp · Heiji Mishkin · Imperatorium · Mack-8 · Reyland Outdoors · Royal Armory

Miscellaneous	Armor Box · Artillery Marker · Breaching Charge · Browning M2 · Care Package Marker · Cleaver · Flare · Flashlight · Gas Mask · Ghillie Suit · Grenade Crate · Halligan Bar · Mk 47 Mod 0 · Mortar · Night Vision Goggles · Parachute · Saw · Sledgehammer · Snowball · Spotter Scope

13.1" First Responder

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