Here is complete guide to the perks found in Call of Duty 4, as well as some personal tactics gleaned from my first few days with the games, as well as from talking to others. The perks are a very satisfying addition to CoD4 in my opinion, and add another level to the game, making it very addictive as you try to collect all the perks that completely change the way you play the game. The levels needed per perk are listed after the perk name ("Start with it" means as soon as you can create a class, level 4).
These were correct as of Patch 1.4 (January 2008).

Perk 1:
C4 Explosives x2 (Start With it)

The C4 Explosives perk gives you two C4 explosives that you throw with the right mouse button and detonated remotely using the fire button, or if you are using your primary weapon you can detonate them by double tapping the USE key. I find this a bit cumbersome with some weapons, but to each his own. In Call of Duty 4, there are no binoculars, so make sure you are aware of your enemyís location before setting them off. C4 Explosives are unlocked as soon as you unlock the Demolitions Class - level 2, Private I.


Special Grenades x 3 (Start With it)

This is my favourite among the Perk 1 group - this one gives you 3 special grenades as opposed to just one. Why is it my favourite? Well, the 3 stun grenades combined with the radar and the ďxĒ indication that shows when youíve hit someone, and itís a great way to find out where people are, run up to them, and knife them with your hobo knife, even from far away! The Special Grenades perk is unlocked by default.


RPG-7 x 2 (Start With it)

The RPG-7 x2 perk gives you two ground-to-air missiles that are very useful for shooting down helicopters. It should also be noted that they can explode cars and other destructible objects on the map, and are very fun to shoot into a group of people. RPG-7's perk is unlocked by default.


Claymore x 2 (23)

Claymores are basically a mine that you can plant in the game to blow people up when they are in range. The claymore packs use light sensors, and typical will be visible before you stumble upon one. The explosion is very directional, and because of this the Claymore perk isnít very useful in situations you would typically use mines. That said, Iíve had good luck hiding these things just around corners out of sight where people canít see the red beams emanating from these things. Claymores are perk is unlocked by default.


Frag x 3 (41)

The Frag x3 perk gives you three frag grenades - simple huh? Not really, once this is unlocked, youíll find the maps littered with grenades - try as you will to pick them up and throw them back, more are on the way! This perk is unlocked at level 41 - Colonel I.


Bandolier (32)

The Bandolier perk gives you much more ammo to start the rounds with, and it goes so well with the Double Tap perk. If you like to sprint around, doing some spray and pray while having a beer like me, this is definitely a must-try. The Bandolier perk is unlocked at level 32 - Captain I.


Bomb Squad (14)

The Bomb Squad perk allows you to detect explosives planted in the map. This is useful if you are up against people who just love using bombs, and have C4 and Claymores hidden throughout the map. Once you know where they are you can destroy them by shooting them, remember you can shoot through walls etc, but when you blow them up they make 1 hell of a noise. The Bomb Squad perk is unlocked at level 14 - Staff Sergeant I.





Perk 2:
Stopping Power (Start With it)

Stopping Power gives your weapon some oompf, and removes the pew-pew! This is a good addition to weapons like the Mini Uzi, that while very fast, certainly lacks power. The Stopping Power perk is unlocked by default.


Juggernaut (Start With it)

The Juggernaut perk, wellÖ makes you a juggernaut! You can take a LOT more damages than usual, and still be standing. Typically this means that I can survive 2 badly fought 1-on-1 rounds and still be running around like a chicken with my head cut off. Juggernaut perk is unlocked by default.


Sleight of Hand (20)

Sleight of Hand helps you to reload weapons a lot faster, and if you canít aim, like to spray and pray, and run around without reloading or watching your ammo, this may be for you. The general idea as to who benefits most to this perk are - shotgun and SAW users (and I have seen it come in pretty handy for Grenade launcher....DIRTY) , but just about any one can use this. Sleight of Hand is unlocked at Master Sergeant I (Lv20).


Double Tap (29)

Double Tap increases the rate of fire for your weapon. This makes some weapons stupidly powerful, like the P90 and the Machine Guns but it also really helps balance things out for weapons that have a slow rate of fire, and makes some weapons like the M16 MUCH better. I highly recommend using this perk with the Bandolier perk as youíll be going through a lot more ammo than usual. The Double Tap perk is unlocked at level 29 (1st Lieutenant I).


Overkill (38)

In my opinion the Perk is VERY over rated, Overkill allows you to START with two primary weapons at once, in the primary and secondary slots. This means you can fulfil your dreams of being a sniper/shotgunner! You simply change weapons to where your pistol would be, and thereís your other weapon. This is great because you can switch weapons faster than you can reload but also because it opens the maps up so that everyone can carry an ACOG weapon as well as an LMG/SMG or what-have-you.
But in my opinion you you just walk up to a dead body and pick it up........


UAV Jammer (11)

The UAV Jammer perk helps to keep you off the radar. when the enemy get 3 kills in a row and then launch there UAV, you still wont show up on the radar, BUT be careful because if you fire an unsilenced weapon you will still show up on the map.  This perk is useful against seasoned players who have become accustomed to watching the radar like hawks, and know all of the hiding places already. I highly recommend trying this with the Dead Silence perk and a silenced gun or knife as you will NEVER appear on the radar then.
You can also use there UAV to your advantage, they will think everyone is showing up on the radar and go sprinting towards the closest red dot, if you wait round a corner for them they will run straight past you. UAV Jammer is unlocked at level 11, Sergeant I.


Sonic Boom (Start With it)

The Sonic Boom perk gives your explosions some added range, and is great when used with the Martyrdom perk because it will see you taking out many people at a time as the grenade you drop will have a larger blast radius. Sonic Boom perk is unlocked by default.





Perk 3:
Extreme Conditioning (Start With it)

The Extreme Conditioning perk allows you to run for a much longer time, and is great in maps where you need to get to a certain point faster than someone else, or when you are trying to escape someone. The amount of time of the increase is roughly 2 times the normal sprint time. Extreme Conditioning perk is unlocked by default.


Steady Aim (Start With it)

The Steady Aim perk give you better aim when not looking down the sights of your gun. When you are running around in CoD4, your head and body bob, and affect your aim much more than in previous Call of Duty games. This perk restores some of the stability found in other CoD games, and makes aiming while moveing that much easier. Steady Aim perk is unlocked by default.


Last Stand (8)

Last stand gives you one last chance to shoot the person who killed you with your pistol sidearm. This can be useful on servers filled with beginners, but players are quickly getting used to finishing people off, gangland-style, because so many beginners are using this. Note that you can use your knife as well, IF they are that close. The Last Stand perk is unlocked early on, at Corpral II (Lv8).


Martyrdom (17)

Martyrdom is one of the most popular perks, and also one of the most annoying. This perk lets you drop a live grenade just after dying, typically killing whoever just tore you up. This has people now sprinting away from corpses, as well as shooting at them just in case they have Last Stand instead. Because of this, if youíre sneaking up on someone who is about to kill someone, be prepared and have your pistol out to shoot them quickly before they run away. Also, if one of your team members has just killed the enemy in a closed room, be careful not to get caught in the door as you both run out. Finally, if you can, try picking up the dropped grenade, and throw it at another enemy. Iíve only been able to do this in open spaces so far, and it needs to be done very quickly, but if youíve just knifed someone, youíll be right on top of the grenade which makes things a bit easier. But you donít knife in wide open spaces, now, do you? Martyrdom is unlocked level 17 - Gunnery Sergeant I.


Deep Impact (Start With it)

A lot of weapons in CoD4 can now shoot through things like corrugated steel, boxes and thin walls. The Deep Impact perk emphasizes this, but also gives lower powered weapons a bit of a boost. Iíve had good results using this and the M16 and the P90. Deep Impact is unlocked by default, as far as I can tell.


Iron Lungs (26)

The Iron Lungs perk is interesting. The whole sniper class has caused quite a stir with Call of Duty fans because it is much harder to snipe in CoD4. This perk helps by allowing you to hold your breath longer, and keep the gun steady. Iím told the real trick to sniping in Call of Duty 4 is to have this perk, hold shift while you aim down the scope, and pause for just a half second longer than normal, and you will hit the mark everytime. Definitely worth trying with the Barret 50cal. Iron Lungs is unlocked at level 26 - 2nd Lieutenant I.


Dead Silence (44)

The Dead Silence perk is my favourite Perk of all........because I love sneaking around maps stabbing people. Dead Silence makes you virtually silent, so that people donít hear floorboards creak as you walk up behind them with your knife out just waiting to slash. Dead Silence is unlocked high level of 44, Brigadier General I, but is definitely worth it, and is amazing when combined with a silenced gun and UAV jamming. Or just use a knife!


Eavesdrop (35)

Eavesdrop is an interesting perk (i cant really see the point to this perk) - it allows you to listen in on enemy chatter as you fight. Iím not sure how you canít hear them already, but this letís you hear them talking about their UAV as well as the bound speech items that some people use. Maybe they use microphones? Anyway, this is a great tool to use against those using stealth perks that make them hard to find on a map, and on the radar. The Eavesdrop perk is unlocked before the dead silence perk as well - you get it at level 35, Major I.