All info about Call of Duty 4 Perks: (2)

Increases weapon damage to 140%, however no increase in wall penetration. This is a great perk to use together with accurate guns that don't do much damage.

For guns with low damage such as the M4 this is a great perk, eliminates juggernaut and to everyone who’s not using juggernaut it just does 40% more bullet damage. Does not increase surface penetration, by definition, but think about this. Let’s say a bullet does 40 damage normally, and after surface penetration does 30. With stopping power, it might do 60 damage normally, but after surface penetration it does 45 or so. So not by definition, but indirectly it increases surface penetration.
Stopping Power is available by default.

Increases your health, taking 75% of the damage from bullets and explosives that is to be originally dealt. If a soldier with Juggernaut is fired upon from a player using Stopping Power, the game calculates it as a perkless fight. Also if a person with Sonic Boom throws a grenade next to someone with Juggernaut, the person with Juggernaut will take regular explosive damage, instead of the increased explosive damage from the Sonic Boom user. This perk is great to use when you like to lay down some cover fire for your teammates. You can keep firing and take a few shots while your teammates get to where they need to go.
How to tell if someone has Juggernaut - When you fire at someone and you see a red cross, it means they are using the juggernaut perk.
Juggernaut is available by default.


Allows reloads at 50% of the original reload time. This perk is great for machine gun users, since it takes a very long time to reload guns like the M60 or the M249 Saw. It is also great for anyone that likes to stay in the heat of battle and reload quickly without having to duck for cover, just to reload.

For pistols it looks like the clip just falls out of the gun and another is crammed in. Probably only a good choice for LMG’s and shotguns, as everything else can benefit more from a different perk 2 usually. Its main use is hardcore, when bullets are 1 or 2 hit kills perk 2 can be kind of useless, so why NOT reload faster? It’s a pretty good deal.
Sleight of Hand is unlocked at Level 20, Master Sargeant 1



Increases your rate of fire to 135%. Put more rounds down range quicker with increased rate of fire on any weapon you have, including your pistol. This perk is ideal for indoor fighting as you do not have to compensate for recoil as much, and can just spray doorways and rooms extremely fast. Warning, although you do fire faster, you waste more ammo and are less accurate if you fire too fast, so you will have to watch the recoil even more with this perk.

Let’s say your gun fires 5 bullets a second, it will now fire 2 more a second (well really 1.75 more a second, but it rounds up to 2, if you want hardcore numbers it's 135% of the normal firing speed). Your clip is emptied faster, but will definitely take down enemies in short order. The epic battle between double tap and stopping power. Here’s how I see it: If you like to get more metal out there and your guns fire rate is bad, go double tap. If you want to make shots count and your fire rate is already decent, go stopping power.
Double Tap is unlocked at Level 29, 1st Lieutenant 1


Overkill allows the player to carry two primary weapons of their choice in the same loadout. The second primary weapon substitutes the pistol. Obviously this perk is great, twice the ammo, and two different guns to choose from. Pick one long range, and one short-medium range weapon and nobody will be able to stop you.

Overrated, I don’t recommend it. The best ways to use it are with a single shot assault rifle (G3 or M14) or with a sniper rifle. For single shot assault rifles, use them to camp, but also overkill them with a great gun for close quarters (skorpion is godly for this) and you’re covered all around. You can also assault with the single shot gun, then run up to close quarters to engage the rest with your other weapon. Snipers tend to like to use this perk with something like the G36C with red dot, something that’s got decent range and good power, and others like to use a purely close range weapon such as an SMG. I personally feel stopping power is a bigger asset to snipers, though, so they can get one hit kills.
Overkill is unlocked at Level 38, Lt. Colonel 1


Allows you not to be seen on the enemies UAV sweep after they get a 3 kill streak. You will still be able to be seen if you fire a weapon unsilenced, however. Great for stealth and hardcore, mainly. Most guns benefit the most from double tap or stopping power to kill faster, but some people think their gun kills fast enough, but they are always getting slayed on UAV. With hardcore and such fast kills, UAV jammer is great. You’re killing people fast enough, so why do you need a killing perk? If you wanna stay off their scans and catch them off-guard as they’re heading to the red dot on their radar this perk is wonderful. Also, to be super stealthy, this will keep you safe.
Unlocked at Level 11, Sargeant 1


Increases the damage dealt by explosives to 125%. Applies to Grenades and C4 as well as the Grenade Launcher.

While it greatly increases explosive range, the maximum explosives you have is two, unless you use overkill with two grenade launcher weapons, but then you can’t use perk 2 and therefore can’t use this perk. Anyhow, so with two explosives, yes while it’s a much bigger explosion and you will have a greater chance to kill people, this will take away a perfectly good perk 2, and after your explosives are gone, you have to fight with your guns raw power. Of course it also applies to grenades too, but you don’t want to have to rely on them. Great perk for completing some of the explosive kill challenges, like killing two people with one RPG, etc. Applies for ALL explosives (except for things like car explosions.)
Sonic Boom is available by default.