"Modern Warfare 4 Multiplayer camo challenges by weapon (pre-launch, to be verified on October 23, 2026)"
Made by PandaPlay - https://mypandaplay.com/modern-warfare-4/guides/mw4-camo-challenges/

Class,Weapon,Special camo 1,Special camo 2,Special camo 3,Gold,Platinum,Harmonic Break,Divergence
Assault Rifles,M4,Lv 26: 20 point-blank kills,Lv 51: 20 kills while mounted,Lv 72: 25 kills from behind,15 kills in one match,50 headshot kills,25 double kills,Unlocked after Harmonic Break on enough weapons in the class
Assault Rifles,Han 86,Lv 25: 20 kills while mounted,Lv 46: 50 kills with a suppressor,"Lv 72: 3 kills without dying, 15 times",15 kills in one match,50 headshot kills,25 double kills,Unlocked after Harmonic Break on enough weapons in the class
Assault Rifles,Hyeon Burst ‡,"Lv 23: 2 kills without reloading, 10 times",Lv 46: 20 longshot kills,Lv 68: 100 kills in full-auto mode †,15 kills in one match,50 headshot kills,25 double kills,Unlocked after Harmonic Break on enough weapons in the class
Assault Rifles,Kastov 762,"Lv 24: 3 kills without dying, 10 times",Lv 48: 20 longshot kills,Lv 71: 30 hipfire kills,15 kills in one match,50 headshot kills,25 double kills,Unlocked after Harmonic Break on enough weapons in the class
Assault Rifles,Patriot XMR,Lv 14: 20 hipfire kills,Lv 49: 50 kills with a suppressor,Lv 72: 30 longshot kills,15 kills in one match,50 headshot kills,25 double kills,Unlocked after Harmonic Break on enough weapons in the class
Assault Rifles,Oden,Lv 25: 25 grenade launcher kills (exact requirement unverified) †,"Lv 44: 2 kills without reloading, 10 times",Lv 65: 100 kills while aiming down sights,15 kills in one match,50 headshot kills,25 double kills,Unlocked after Harmonic Break on enough weapons in the class
Assault Rifles,Axion,Lv 23: 20 longshot kills,Lv 45: 25 grenade launcher kills (exact requirement unverified) †,"Lv 69: 2 kills without reloading, 10 times",15 kills in one match,50 headshot kills,25 double kills,Unlocked after Harmonic Break on enough weapons in the class
Assault Rifles,Cronen Squall,Lv 24: 20 point-blank kills,Lv 45: 20 kills while mounted,"Lv 67: 3 kills without dying, 15 times",15 kills in one match,50 headshot kills,25 double kills,Unlocked after Harmonic Break on enough weapons in the class
Submachine Guns,ISO Nightshade,Lv 22: 50 kills while aiming down sights,Lv 44: 10 double kills,Lv 64: 15 longshot kills,15 kills in one match,25 kills from behind,50 hipfire kills,Unlocked after Harmonic Break on enough weapons in the class
Submachine Guns,VEL 46,Lv 20: 20 kills while prone,Lv 40: 20 kills while prone,Lv 60: 20 headshot kills,15 kills in one match,25 kills from behind,50 hipfire kills,Unlocked after Harmonic Break on enough weapons in the class
Submachine Guns,WZ.55 Striga,Lv 20: 50 kills with a suppressor,Lv 41: 20 kills while jumping,Lv 60: 40 point-blank kills,15 kills in one match,25 kills from behind,50 hipfire kills,Unlocked after Harmonic Break on enough weapons in the class
Submachine Guns,PPSh-41,Lv 20: 10 double kills,Lv 41: 20 longshot kills,Lv 82: 100 kills while aiming down sights,15 kills in one match,25 kills from behind,50 hipfire kills,Unlocked after Harmonic Break on enough weapons in the class
Submachine Guns,X-58 Nyx,Lv 17: 20 kills while moving,Lv 35: 20 longshot kills,Lv 53: 40 headshot kills,15 kills in one match,25 kills from behind,50 hipfire kills,Unlocked after Harmonic Break on enough weapons in the class
Shotguns,Rezi 12,Lv 22: 20 point-blank kills,Lv 42: 10 longshot kills,Lv 60: 40 kills while jumping,15 kills in one match,125 hipfire kills,"2 kills without reloading, 25 times",Unlocked after Harmonic Break on enough weapons in the class
Shotguns,Warlord,Lv 21: 20 kills while moving,Lv 41: 10 double kills,Lv 60: 50 kills while prone,15 kills in one match,50 hipfire kills*,"2 kills without reloading, 25 times",Unlocked after Harmonic Break on enough weapons in the class
Light Machine Guns,FINN,Lv 18: 20 point-blank kills,"Lv 39: 2 kills without reloading, 10 times",Lv 60: 30 longshot kills,15 kills in one match,"3 kills without dying, 15 times","2 kills without releasing the trigger, 25 times",Unlocked after Harmonic Break on enough weapons in the class
Light Machine Guns,Type 73,Lv 23: 20 kills while mounted,Lv 45: 10 double kills,Lv 65: 40 headshot kills,15 kills in one match,"3 kills without dying, 15 times","2 kills without releasing the trigger, 25 times",Unlocked after Harmonic Break on enough weapons in the class
Light Machine Guns,APOC-338,Lv 15: 20 hipfire kills,Lv 36: 20 longshot kills,Lv 56: 100 kills while prone,15 kills in one match,"3 kills without dying, 15 times","2 kills without releasing the trigger, 25 times",Unlocked after Harmonic Break on enough weapons in the class
Marksman Rifles,MAR-9,Lv 26: 20 kills while mounted,Lv 49: 25 kills while crouched,Lv 73: 30 longshot kills,15 kills in one match,75 kills while prone,75 one-shot kills,Unlocked after Harmonic Break on enough weapons in the class
Marksman Rifles,Oris 8.6,Lv 27: 10 quickscope kills,Lv 49: 20 double kills,"Lv 70: 3 kills without dying, 15 times",15 kills in one match,75 kills while prone,75 one-shot kills,Unlocked after Harmonic Break on enough weapons in the class
Marksman Rifles,Mosin-Nagant,Lv 25: 25 headshot kills,15 longshot kills,20 headshot kills,15 kills in one match,75 kills while prone,75 one-shot kills,Unlocked after Harmonic Break on enough weapons in the class
Sniper Rifles,KG-7 Vulcan,Lv 22: 10 hipfire kills,Lv 47: 20 headshot kills,"Lv 75: 2 kills without taking damage, 20 times",15 kills in one match,75 kills while prone,75 one-shot kills,Unlocked after Harmonic Break on enough weapons in the class
Sniper Rifles,Astaroth .57,"Lv 20: 3 kills without dying, 10 times",Lv 37: 20 kills while mounted,"Lv 54: 2 kills within 5 seconds, 20 times",15 kills in one match,75 kills while prone,75 one-shot kills,Unlocked after Harmonic Break on enough weapons in the class
Sniper Rifles,Signal .50,"Lv 28: 2 kills within 5 seconds, 10 times",Lv 52: 20 quickscope kills,Lv 74: 40 longshot kills,15 kills in one match,75 kills while prone,75 one-shot kills,Unlocked after Harmonic Break on enough weapons in the class
Pistols,Sang 9mm,Lv 13: 25 kills while aiming down sights,"Lv 25: 3 kills without dying, 5 times",Lv 38: 50 akimbo kills,15 kills in one match,20 kills from behind,40 hipfire kills,Unlocked after Harmonic Break on enough weapons in the class
Pistols,Krait P68,Lv 13: 15 kills while hanging †,Lv 25: 15 point-blank kills,Lv 38: 30 kills with a suppressor,15 kills in one match,20 kills from behind,40 hipfire kills,Unlocked after Harmonic Break on enough weapons in the class
Pistols,.50 GS,Lv 18: 25 headshot kills,Lv 34: 7 double kills,Lv 50: 30 point-blank kills,15 kills in one match,20 kills from behind,40 hipfire kills,Unlocked after Harmonic Break on enough weapons in the class
Pistols,Mojave .357,Lv 16: 15 one-shot kills,"Lv 30: 2 kills without reloading, 10 times",Lv 44: 30 point-blank kills,15 kills in one match,20 kills from behind,40 hipfire kills,Unlocked after Harmonic Break on enough weapons in the class
Launchers,PILA,Lv 16: 10 direct-impact kills,Lv 31: 5 double kills,Lv 46: Destroy 30 scorestreaks or vehicles,15 kills in one match,"2 kills without taking damage, 15 times","10 kills in a single match, 7 times",Unlocked after Harmonic Break on enough weapons in the class
Launchers,RPG-8,Lv 16: 10 direct-impact kills,Lv 31: 10 longshot kills,Lv 46: Destroy 30 scorestreaks or vehicles,15 kills in one match,"2 kills without taking damage, 15 times","10 kills in a single match, 7 times",Unlocked after Harmonic Break on enough weapons in the class
Launchers,JOKR,Lv 16: 5 double kills,Lv 31: 10 longshot kills,Lv 46: Destroy 30 scorestreaks or vehicles,15 kills in one match,"2 kills without taking damage, 15 times","10 kills in a single match, 7 times",Unlocked after Harmonic Break on enough weapons in the class
Launchers,PM-40 Anvil,Lv 16: 25 direct-impact kills,"Lv 31: 2 kills without reloading, 5 times",Lv 46: 40 kills while moving,15 kills in one match,"2 kills without taking damage, 15 times","10 kills in a single match, 7 times",Unlocked after Harmonic Break on enough weapons in the class
Melee,Combat Knife,Lv 16: 25 kills while jumping,Lv 31: 25 heavy melee executions †,"Lv 46: 2 kills within 5 seconds, 25 times",15 kills in one match,"3 kills without dying, 15 times",25 kills from behind,Unlocked after Harmonic Break on enough weapons in the class

"* Warlord Platinum: this sheet lists 50 hipfire kills; the shotgun class rule elsewhere is 125. Unresolved, check in-game."
† Translated from a pre-launch sheet; exact in-game wording not yet checked (the grenade launcher entries could refer to a 40mm launcher or a 40-metre range. ‡ Weapon-name mapping unverified).
Source page: https://mypandaplay.com/modern-warfare-4/guides/mw4-camo-challenges/