M16A4

The Colt M16A4 is a lightweight, shoulder-fired, magazine-fed, gas-operated, air-cooled, assault rifle chambered for the 5.56x45mm NATO cartridge, and is the current standard issue rifle of the United States Marine Corps and some United States Army units. It is the current iteration of Eugene Stoner's original design, preceded by the -A3, -A2, and -A1 variations. The M16A4 rifle differs from the M16A2 in that it has a MIL-STD-1913 Picatinny rail under the removable carrying handle which allows different types of optics to be mounted on the top of the receiver, as well as a thicker barrel. There are also Picatinny rails mounted on the handguard to allow lasers, flashlights, and foregrips. The M16A4 is capable of semi-automatic and burst fire. The US military purchases M16A4s from Colt and FN Manufacturing with most M16s in recent orders being made by FN. In addition, M16 receivers for sniper variants and special purpose weapons have been procured from ArmaLite and Knight's Armament Company. The M16A4 is light and accurate, but requires frequent cleaning, partially because it is susceptible to dirt, but also because its internal mechanism lacks a piston; the gases strike the bolt of the rifle directly. This method of operation results in a lighter, simpler rifle, but causes fouling issues as carbon is blown into the chamber of the weapon.

Call of Duty 4: Modern Warfare
In singleplayer, the M16A4 can only be picked up during War Pig. It is dropped occasionally (sometimes with the M203) by dead Marines, and always uses iron sights. If you find a grenadier vesion and have found all the intel items, the M16 grenade laucher fires on full auto faster than any other grenade launchers in the game. The M16A4 in singleplayer has a fully automatic firing mode though in reality the A4 variant features only three-round burst fire (but it is possible to modify one to fire fully automatically either with a full auto trigger group, or a little machining). It is also used by Lt. Vasquez.

In multiplayer, the M16A4 is available at level 1 and fires in three-round bursts. It can be fitted with a Silencer, Red Dot Sight, ACOG Scope, and M203. It is also fairly similar to the M4 Carbine, as it has the same appearance, the same iron sights, and they also share ammo with each other, as well as with the G36C, however, the M16 has noticeably higher damage than the M4.

Usage
It is often recommended to use this weapon from a distance as it is not considered effective in close quarters combat. When fired from the hip while moving the M16A4 is wildly inaccurate. Unlike most other semi-automatics like the G3 or pistols, which can be fired as quickly as the user can pull the trigger, the M16A4 has a forced delay between bursts. This delay effectively lowers the rate of fire in terms of adjusting aim meaning that at close range if the first burst misses the user will be dead before getting off a second burst. However, Steady Aim shrinks the hip fire reticle to sizes comparable to SMGs making the weapon fairly accurate from the hip even while moving. Thus, even at close range a Steady Aimed, Stopping Powered M16A4 user can be very effective if they can land the first, often deadly, burst.

The M16A4 is exceptionally powerful because all the bullets in the three rounds have a damage of 30-40 each meaning most of the kills will be one hit or two hit kills. When used with Stopping Power, the M16 is able to kill in one burst at any range provided that all three shots hit the target (only two are needed at medium and close range) and the target is not behind a wall or using Juggernaut.

Double Tap decreases the delay between the firing of each of the three bullets in a single burst and decreases the amount of time between bursts. With Double Tap, all of the rounds fired in a single burst are now fired with hardly any delay between shots. This can be somewhat useful in many situations, as there is a higher chance of all three bullets hitting the target and the shorter time between bursts makes the weapon more effective in CQB. However, Stopping Power is still considerably better as if each shot hits it will count as a kill, except in Hardcore modes.

The M16A4 is widely considered to be one of the best rifles in the game due to its power, accuracy (due to tiny recoil and no red dot sway), quick reload, relatively quiet report and mobility. This makes it popular to use, but is also frowned upon by some players due to the ease of achieving kills without putting much effort in, which is also the reason people use it. Some also choose to avoid it because of Juggernaut users.

Call of Duty 4: Modern Warfare (Nintendo DS)
In the Nintendo DS version of Call of Duty 4: Modern Warfare, the M16A4 appears as one of the two assault rifles in game. The M16 bears a vague resemblance (though it can still be identified as a M16) to the one in the console versions, though it fires fully automatic (like the M16s in Call of Duty 4 campaign mode). It has a much slower rate of fire, but it does more damage per bullet to compensate for this. In single player, the M16 is only found with a holographic sight, as opposed to iron sights in multiplayer. This doesn't matter, since the iron sights are just as accurate as the holographic sight, and provide a better peripheral view. In single player, the M16 is most effective at long range, though it is still effective at close-medium range. This all changes in multiplayer, as it is only effective at long ranges. It's low rate of fire prevents it from being effective at close range, unless the enemy doesn't see you. The M16 also has the third slowest melee speed, making it even less effective in close encounters.

Call of Duty: Modern Warfare 2
The weapon has returned in Call of Duty: Modern Warfare 2. It behaves similarly to Call of Duty 4: Modern Warfare with some small differences. It is now unlocked at level 40 in multiplayer and its reload animation is now identical to that of the M4A1 Carbine. To make it look more modernized, a Picatinny Rail has been placed on the carrying handle, and RIS with rail covers. The rear sight aperture has been made thinner than the Call of Duty 4: Modern Warfare version, making the iron sights much easier to operate. Also, camo now only appears on the barrel and any attachment.

The FAMAS is similar to the M16A4 as they share nearly identical stats. The FAMAS takes 1.08 seconds longer to reload (.16s empty), but has less damage drop off than the M16A4, leading to an increase in medium range performance. When a Holographic Sight is attached to the M16A4, the recoil is reduced.

In single player, the M16A4 is seen in both American and Task Force 141 missions, although the FAMAS is much more predominant. It fires in bursts in both singleplayer and multiplayer, unlike its Call of Duty 4 counterpart which was fully automatic in the singleplayer.

Weapon Attachments

 * Grenade Launcher (Marksman I - 10 kills)
 * Shotgun (20 kills with the Grenade Launcher)
 * Red Dot Sight (Marksman II - 25 kills)
 * EOTech Holographic Weapon Sight (60 kills while aiming down the Red Dot Sight)
 * Silencer (Marksman III - 75 kills)
 * Heartbeat Sensor (15 kills with the silencer attached)
 * ACOG Scope (Marksman IV - 150 kills)
 * Thermal Scope (20 kills while aiming down ACOG)
 * FMJ (Full Metal Jacket) (Marksman V - 300 kills)
 * Extended Mags (40 kills with Bullet Penetration while using FMJ)

Trivia

 * In Call of Duty 4, The words "BLUE4" (a reference to BluFor, the opposite of OpFor, which is applied to all NATO forces) and "Property of U.S. Government, Caliber 5.55x45mm NATO, M4A1 Carbine" in bold blue letters is visible on the side of the M16A4. The M16 fires 5.56x45mm NATO cartridges (5.55 is likely a typo) and the M4 Carbine was derived from the M16 series. This error is fixed in Modern Warfare 2.
 * Individual bursts fire as fast as the P90 and M249 SAW, making it an unusually fast-firing Assault Rifle.
 * In Call of Duty 4, the M16 had its own reloading animation. In Modern Warfare 2, its reloading animation is the same as the M4A1.
 * In multiplayer, if the player attaches the grenade launcher to the M16A4, the heat shield turns into the one that was used for mounting the M203 onto M16A2s. This is unnecessary, as the M5 RAS used on the M16A4 is just as capable of mounting the M203. This does not necessarily indicate that it turns into an M16A2, since it is one part that is very easy to swap out, and it still has the A4's removable carrying handle. This is fixed in Modern Warfare 2.
 * In Call of Duty 4, if the Infinite Ammo cheat is enabled and an M16 is picked up with the M203, the fully-automatic rate of fire of the grenade launcher is very, very fast and greatly surpasses that of the M4A1. Curiously, the M203 on the M4 Carbine and the GP-25 on the AK-47 have much slower fully-automatic rates of fire, about the same as the W1200.
 * The M16A4, FAMAS, and the M93 Raffica are the only weapons in the Call of Duty series that fire in bursts.
 * The Call of Duty 4 in-game model depicted the M16A4 having an A4 upper receiver, but has an A1 lower receiver, which explains why the weapon can go full-auto in single player.
 * In Call of Duty 4: Modern Warfare (DS), the M16 has a Red Dot Sight in single player.
 * When an M203 is attached the forward iron sight changes size.
 * In Call of Duty 4 DS, even though the M16 fires fully automatic for the player, allies fire it in a three-round burst. This is the same with most weapons, even those used by enemies.
 * In Modern Warfare 2, the side of the M16A4 says, "Made By Infinity, Tool For Victory, U.S. No Refunds".
 * In Modern Warfare 2, the M16 is completely missing the upper receiver on the right.
 * In the level War Pig in the first Modern Warfare, anytime you switch your secondary weapon with an M16A4 Grenadier, the amount of grenades increases, however, if you switch either your M4A1 Grenadier or the M16A4 Grenadier with the non-grenadier version, you will lose a significant amount of grenades.
 * The Iron Sight in both games are in position for short range aiming (0-200 aperture), in which the rear sight can be flipped up and down to adjust for targeting range.
 * The M16A4 is not used by the US Army Rangers since they are replacing their M4s for the newer SCAR series. The M16A4, however, is used by some infantry units in the U.S. Army and is standard issue in the Marine Corps. (Every Marine is trained to fire 10 perfectly aimed rounds with the M16A2 from 500yds in Marine Corps Recruit Training)
 * In the Modern Warfare 2 level "Of Their Own Accord", an M16A4 w/ Red Dot Sight can be found in the bunker in the beginning and dropped by soldiers in the 'killzone'.
 * The iron sight on the M16A4 in Call of Duty 4 limits peripheral vision and the front sight is slightly higher up than in Modern Warfare 2.
 * In MW2 and MW1, setting the sensitivity to 10 and spinning to the right reveals a complete lack of texture on the right side of the gun, as it shouldn't technically be seen.
 * In Modern Warfare 2, when looking at the right side of the M16 in either third person or when dropped, there is no forward assist, but all other components to the right side of the receiver remain (ejection port, brass deflector, magazine release etc).
 * In Modern Warfare 2, the rifle's rear sight is higher than it should be.
 * In Modern Warfare 2, if you pick up this weapon, or take it out for the first time, the player will not pull the charging handle back. This is inaccurate because the M16 shares the same operation with the M4A1.
 * The soldier on the cover of Modern Warfare 2 carries a M16A4 with the ACOG scope.
 * In Modern Warfare 2 the pickup icon for the M16A4 shows it with a M203 grenade launcher attached regardless of attachments.
 * In Modern Warfare 2's campaign, the M16A4 can only carry a maximum of four 40mm grenades when equipped with an M203, where as weapons like the SCAR-H and M4A1 can hold a maximum of 11.