M4 carbine

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The M4 carbine is a dual perk assault rifle depicted in two fashions within Killing Floor; the first is a scoped variant listed as a Commando weapon, the second featuring no scope and a M203 model 40mm grenade launcher is listed as a Demolition perk weapon. Both function the same for the Commando perk, save for the bonus damage, scope, total ammo reserve, and grenade launcher, who also receives discounts on the cheaper scoped variant. The Demolitions perk gets discounts on the more expensive M203 variant, and receives damage bonuses on the launched grenades, which essentially functions identically to the M79 grenade launcher for virtually all respects.

Both weapons have separate ammo pools, and are interchangeable for the Bloody Yanks achievement. On the 23rd of October 2013, a special Camouflage Weapons DLC was released, containing new skins for some of the older weapons, including this one. This particular weapon was fitted with MARPAT digital desert camouflage.


Trader M4.png
Pricing: £1000 (£750)
Weight: 6 blocks
Ammo: 30 Hud Ammo Clip.png 13 (400)
Ammo cost: £10 – £133
Related achievements
Bloody Yanks.jpg Bloody Yanks

The M4 is the Commando specific variant of the weapon. It comes with a larger ammo pool, and an aimpoint sight. It is functionally similar to the AK-47 but with slightly tighter spread, faster fire rate, less damage, and more total ammunition. It also has the ability to toggle fire from semi to fully-automatic fire, as with all other Commando weapons. Abundant ammo pool gives this weapon a great sustainability but zed-time extending capabilities still limited for the perk due its low damage per shot and recoil. Rifle usually covers its long reload times by staggering the horde by leaving flimsy specimen at the front to bleed out by weak decapitations from a distance. The Demolitions perk receives no bonuses at all for using this weapon unlike a Commando wielding the M4/203.


M4 203
Trader M4 203.png
Pricing: £2750 (£2062)
Weight: 6 blocks
Ammo: 30 Hud Ammo Clip.png 9 (300)
Hud M79.png 12
Ammo cost: £10 – £100
Related achievements
Bloody Yanks.jpg Bloody Yanks
Finish Him.jpg Finish Him

The M4 203 is the demolition specific variant of the weapon. It has a lower ammo pool than the Commando variant, costs more, and loses the ability to toggle fire mode to semi automatic due to the under-slung M203 grenade launcher it features to replace the toggle. M203 variant can only shoot in three bullet bursts and can not exhaust a magazine full-auto, neither switch to semi-auto mode. It also lacks the aimpoint optic sight the other variant features that the trader image erroneously depicts atop, which instead featuring basic iron-sights. When used by a Commando the damage bonus and bigger ammo reserve applied to the normal M4 does not apply to the M4/203; however, it does feature less recoil and larger magazines from the perk. A high level Commando will have fewer total magazines than a lower level or a Demolitions due to more bullets being available in each magazine.


The commando and demolition perks both get bonuses and discounts for variants of the M4. The Bullet damage and Magazine size columns apply to the commando, the Grenade damage, Price and Sale value columns apply to the demolition perk.

Level  Discount Price Sale value Bullet damage Grenade damage Magazine size
Base 0% £2750 £2062 35 350 30
0 10% £2475 £1855 36 367 30
1 20% £2200 £1649 38 385 33
2 30% £1925 £1443 42 420 36
3 40% £1650 £1237 45 455 37
4 50% £1375 £1030 49 490 37
5 60% £1100 £824 52 525 37
6 70% £825 £618 52 560 37

Price and ammunition[edit]

The standard variant of M4 costs the same as the AK-47; £1000 with discounts for commandos of £100 per level down to a current minimum of £300. Conversely the M4 203 is one of the most expensive weapons in the game, with a base cost of £2750. Discounts are given to demolitions players of £275 per level to a current minimum of £825. The ammunition costs £1 for three bullets, equating to £10 per magazine of thirty bullets. The M203 grenades cost £10 each; the same as the grenades in the M32 and M79, and can be stocked up to twelve.

At levels 3 and above with commando the magazine capacity is increased to 37 bullets. The total ammo reserve of the M4 increases with this accordingly to from 400 bullets to 500, however the ammo reserve size of M4 203 remains static.


The base damage for the M4's primary fire is 35 per shot; that's in the middle, compared to 26 of the bullpup and 45 of the AK-47. However, it actually has the highest rate of fire of the assault rifles with RPM of 750, so its active before reload DPS is actually higher than that of the AK-47 and Bullpup. While M4 loses its damage per second after reload, its large ammunition pool makes up for it to sustain.

When fired off perk, M4 will deal 1050 damage over the course of 2.32 seconds, this makes an impressive 452.6 dps while after reload it reduces down to 198.5 damage per second. When fired by a level 6 Commando, scoped M4 deals 1924 damage over the course of 2.88 damage before reload which makes up for 668 damage per second before reload. After reload dps reduces down to 406.2 over 4.74 seconds. M203 variant M4 will suffer slightly lower damage per second from automatic fire because its reload time is slightly lengthier than scoped M4 variant; M4/M203 has 3.63 second magazine reload while scoped M4 has 2.97 seconds and firing in bursts which paces away the tripplet bursted bullets. While offering a huge damage per second, bearer should remember M4 recoils and showing matching performance to its theoretical damage depends on recoil mitigation or controlling it.

The M203 grenade launcher on the demolition variant functions identically to the M79 grenade launcher, save for its smaller grenade stock of 12 total compared to M79's abundant 24 shots. M203 grenade loads up in 3.33 seconds and shares the same reload time with M79. Demolition perk receives up to 60% damage bonus for grenades while Commando can reload them faster.


The scoped M4 has a notably high rate of fire, and is often frowned upon by most users of the weapon. However, one can notice that the recoil is greatly increased while moving. The best tactic while using the fully automatic fire mode is to stand stationary and/or crouch down to improve accuracy. Crouching or standing still is not recommended where you can get overwhelmed or cornered easily. Because of low damage, single-fire mode only happen to be effective from long ranges. Other than that, it's also not recommended to keep the weapon on single fire at close combat unless you need to manage ammo, keep moving and time your reloading by eliminating last specimen around. M4 single fire will give you large enough space to work when you're holding a narrow choke from a reasonable distance, stay on the move to decide when to burst down and allow you to manage reloads the moment you soft decapitate a low-medium threat such as Gorefast or Bloat. At the vast open areas, long reload and weak bullet damage will create a conundrum and require you to use grenades to get out from sticky situations and exhaust the magazine quickly in bursts to move forward.

The M203 mounted on the Demolitions variant of the weapon is extremely useful for crowd control. Using the automatic fire mode, the player can easily do away with individual, weak enemies such as Clots and Crawlers. The grenade launcher secondary fire is most effective on incoming hordes of Gorefasts and Stalkers. In order to deal with large enemies such as Fleshpounds and Scrake, both the automatic and secondary fire mode must be utilized. 40mm M203 grenade shots often required to be paired with hand grenades to set off stacked bunches for dealing proper damage to Fleshpounds or dispatch ranged threats like Husk and Siren quickly. Specimen with above mediocre health such as Gorefast and Siren might survive a direct 40mm grenade shot from the M203 but follow up bullet bursts can kill them.

Pipebombs can be detonated from afar by shooting them before anything sets them off. 40mm grenade headshots can be utilized to put a Scrake in a slow moving enrage state by heavy flinching them, close to their enrage threshold at the hands of a level 3 and above Demolition. This requires Scrake to not suffer any sort of stun or another heavy flinch before hand to work. Ideally after a few bursts from M4, a hand grenade tossed at their upperbody can be set off with a well put M203 headshot to do it instantly. M203's very limited grenade shot supply should be treated as an extension to the main weapon's destructive capacities as it can easily set off grenades as much as pipes and allow one to cycle weapons faster than M79 after sending a thumper.

For off-perk use with Commando or as Support Specialist, 40mm grenades from M203 can be used for mini-flinching a Scrake momentarily from close quarters before going in point blank and finishing them off with a high burst weapon such as SCAR or Hunting shotgun. After flinching the Scrake, an intentional missing automatic fire required to cancel the reload animation of M203 shot, so weapon switch could be done quicker rather than awaiting the reload. If bullet burst of M4 shot at Scrake directly, this will cancel his flinched state early and he may step forward to punish you for it.

For off-perk using the scoped M4 solely, Field Medic or Berserker can have it as a side arm to level up Commando perk or extending zed-time while still keeping it safe. Still, the lengthy reload of scoped M4, sure leaves better options on the field and will not allow a hectic playstyle as difficulty rises. The weak damage per shot, potential spread with rapid fire rate and lengthy reload, doesn't allow one to prioritize targets at distance. When offperk, scoped M4 should be kept at semi-auto most of the time for best results and full auto only should be switched to when there are weak close by targets that you need to dispatch quickly. Considering MAC-10 deals same damage per shot, allows grenade tossing faster and weighs less, scoped M4 hardly has any place for off-perk use. If a reliable assault rifle needed for MKb, AK-47 and SCARMK17 are much better candidates performance wise to the M4 scoped.

Advantages & Disadvantages[edit]


  • An all-rounder weapon;
  • Accurate, only when stationary;
  • The view model is stable with less sway on the move;
  • Reliably decapitates lesser specimens;
  • Generous ammo pool for Commando with M4, at both variants;
  • Semi-automatic and fully-automatic firing modes (for Commando M4 only);
  • Most accurate Commando weapon in semi-automatic;
  • High rate of fire rewards controlled bursts are rewarded;
  • Headshots leave Gorefasts to bleed out to stall others;
  • Can dispatch a Siren with a quick tap to silence then dump the rest of the magazine easily;
  • Underbarrel M203 grenade launcher for added versatility and power (for M4 203 only);
  • M4/M203 benefits from larger magazine bonus of Commando just like a perk weapon;
  • M203 grenade shot can set grenade stacks off in the vicinity of the blast increasing the damage burst;
  • Blunt grenade shots from up close can flinch or heavy flinch a Scrake at the hands of a Demolition;
  • Long ranged explosive grenade shots can clear crowds;
  • Only 6 kg of weight on both scoped and M203 variant.


  • Loses to other higher caliber auto rifles at off-perk use;
  • Weak damage per shot;
  • Weak against stronger specimens like Scrake, Fleshpound and Patriarch;
  • High recoil in full-auto fire;
  • Rapid fire rate drains magazines quickly;
  • Bullets do not penetrate;
  • M203 grenade launcher is a single fired armament and slow to reload;
  • Long magazine reload time punishes your misses further;
  • Low decapitation damage bonus;
  • Single burst from M4/M203 is not strong enough to kill a single Crawler by bodyshots only;
  • M4 203 is expensive compared to alternatives like a medium grade single pistol with M79;
  • M4/M203 gains no bullet damage or recoil mitigation bonus from Commando perk;
  • Low ammunition for Demolition with M4 M203;
  • Low grenade shot count for Demolition with M4 M203;
  • No select-fire option on M4 203;
  • Iron sights on M4 203 are not as effective as the scope on the regular M4;
  • Heavy at 6 kg for the offered fire power for their respective perks.


  • The 40mm grenade fired from the M203 is actually fired from the muzzle of the weapon, instead of the underslung grenade launcher. This can easily be seen by using the slow motion function or when fired during ZED mode.
  • One can empty the magazine of the weapon, start the reload, and fire the M203 before the reload is finished, thus canceling out both reload animations.
  • The pickup/trader icon for the M203 variant is incorrect. The in-game model does not have an M68 Red Dot Sight.
  • If the M4 203 is bought before the M4, then both guns will share the lower, 300 rounds ammo pool of the M4 203. This can be fixed by dropping both weapons, then picking up the M4 first, followed by the M4 203.


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