Call of Duty: Modern Warfare 2
In Comparison to Other Weapons
In Modern Warfare 2, the M4A1 has two direct competitors, the SCAR-H and ACR.
The SCAR-H has less recoil, higher damage (40-30), a lower rate of fire (630 RPM), and a smaller magazine (20 rounds). Its higher damage is enough to make up for its lower rate of fire in that the SCAR-H will always kill faster than the M4A1 if all shots hit and its lower recoil makes it more accurate at longer ranges. However, its small magazine makes it less capable of engaging multiple targets in rapid succession. In essence, this means that the SCAR-H is superior at engaging single targets while the M4A1 is better at engaging multiple targets.
The ACR has a slightly lower rate of fire than the M4A1 (750 RPM) and no recoil. Ostensibly there is little reason to use the M4A1 upon unlocking the ACR, as the ACR's total lack of recoil is a far greater advantage than its lower rate of fire is a disadvantage. This means that the only times the M4A1 will beat the ACR are when firing from the hip or when shooting at targets that are close enough to ensure that the M4A1's recoil will not be enough to cause any missed shots.
The weapon has zero idle sway, with any attachments, apart from the Thermal Sight. This contrasts with the appearance in CoD4, and as a result, the M4A1 is useful at much longer ranges than its older-game variant.
Perhaps one of the most common attachments used with the M4 is the Red Dot Sight. The ironsights can be slightly obtrusive at the sides, as there is a large aperture, which is used for aiming. The ironsight is similar to the SCAR-H's in its shape, however the aperture makes it less clear. The Ironsights are more useful at close-range, where vision is not blocked as much; at long range targets may be moving and seeing other threats may be impossible. The Red Dot makes for more precise aiming, as well as a much clearer view.
The M203 Grenade Launcher is also a useful attachment to the M4; it helps it clear targets at longer range due to the explosive nature of the attachment, as well as a backup if ammunition runs low.
The Thermal Scope is not a recommended attachment; the scope is usually used for longer ranges, and as the M4 is a lower-damage Assault Rifle, it is not useful at range, especially as recoil is also increased while using the Thermal.
Bling allows a player to pair attachments on the M4A1, the M203, when paired with the Red Dot Sight can make an effective weapon for providing suppressing fire. The silencer can also be paired with any of the sights to provide an effective close-quarters stealth weapon.
The M4A1 benefits being paired with launchers, as it's high rate of fire and fairly good accuracy make it a proficient close-quarters weapon. Though it's lower damage and high rate of fire pair together and can lead a player to easily burn through ammunition, meaning that a sidearm (such as the USP .45) can be useful against enemy rushers. It is useful though if the M4A1 runs out, switch to a shotgun like the SPAS-12 or the M1014 to fire at close range.
Usefulness of Weapon Attachments
Grenade Launcher: A 40mm M203 grenade launcher- The grenade launcher is incredibly useful on the M4A1 especially as it can clear out positions that would be inconvenient/hard to do with the M4A1. The M203 is extremely useful for clearing out sniper/machine gun positions while having a rifle that can pack a punch at hand. 9/10
Red Dot Sight: A reflex sight- The Red Dot Sight (RDS) may or may not be useful depending on playstyle and the user's opinion of the gun's standard sights. The RDS is actually useful on the M4A1 as it provides better peripheral vision than the original sights while allowing quick target aquisition. But again, depending on the user's opinion of the gun's metal sights, it may or may not be a waste of an attachment. 7/10
Silencer: A barrel attachment which dampens noise and flash produced by the gun- The Silencer isn't really an attachment that stands out as a better attachment than the other ones. But it has a few advantages like dampening noise and making the iron sights easier to use because it reduces flash. But overall, this attachment isn't the best and taking another attachment may prove better. 6/10
ACOG scope: A 4× magnification sight- An optical attachment that allows further vision, but this comes at the expense of minimal recoil increase and worse reaction time when aimed down the sights. Also, the ACOG is ineffective in close engagments. The ACOG, though, is rather remarkable as it doesn't increase the M4A1's recoil by much while increasing the range of the weapon. But there is no reason that you "should" use it over other optical attachments which may or may not do the same. 5.5/10
FMJ: Higher penetrating bullets- FMJ is probably the worst attachment to use on the M4A1. Contrary to popular belief, FMJ does NOT increase damage at all, just penetration. FMJ isn't a bad attachment, it's just useless unless you're going for extended mags. Considering the M4A1 has pretty high penetration, FMJ is good for extended mags at best. 4/10
Shotgun: Underbarrel shotgun- The Shotgun attachment is questionable on the M4A1 considering the M4A1 already has a high fire rate making it useful for CQC. But the underbarrel shotgun may be a good attachment as it allows for a person to drop a guy in one shot or at least quicker than they can with the M4A1. Overall, a decent attachment. 7.5/10
Holographic Sight: A holographic reflex sight- The Holo sight is basically Red Dot Sight v2.0. The holo sight is in every aspect better than the RDS except for the fact that it makes the gun look in some cases uglier looking, but the technical advantages will far outweigh this. The holo sight has a larger red dot allowing for even easier target aquisition and ADS sensetivity is somewhat greater allowing for better CQC capabilities. Overall, a great optical attachment. 8.5/10
Heartbeat Sensor (commonly abbreviated as HBS): A monitor which contains a sensor that senses heartbeats nearby- The HBS is very, very useful for going into close quarters or infiltration. These qualities also mark the strongest points of the M4A1 further making this a desirable. The heartbeat sensor can tell where enemies are. The only real problems are that the heartbeat sensor may be distracting and that it's completely not visible in 3rd person modes. But the monitior beeps so you can use it as a referencing tool instead of a precision instrument. 9/10
Thermal Scope: A thermal imaging optical sight- The Thermal scope is somewhat good and somewhat bad. The Thermal allows for greater aquisition of targets for longer ranges and in dull-colored maps like wasteland and the recoil isn't as great as it would be with other thermal-sighted assault rifles. But the Thermal scope takes the M4A1's greatest strongpoint (low recoil and high accuracy) and washes it down the drain. The thermal scope on the M4A1 is horrible at long range, also considering that the M4A1's stopping power isn't very high, and that at those farther ranges, any LMG, Sniper rifle will shoot you first. Although the thermal scope is effective at medium range, using a holo sight, red dot sight, or even an ACOG sight is better at those ranges as it does not block peripheral vision as much. Overall, unless you're spotting targets or really good at sniping with the M4A1, don't use it. 6.5/10
Extended magazine: An extended magazine with a higher round capacity- Extended mags gives the M4A1 45 rounds in one magazine. Extended mags may or may not be a good attachment. The increased capacity lets the user reload less times and it gives the user a second chance if their aim is bad. But depending on how you play, extended mags may turn out to be outright useless as it promotes spraying and most players reload after a few kills anyways. Although extended mags is a great defensive attachment, it's offensive capability is significantly hampered by better attachments such as the grenade launcher and shotgun and optical attachments. Overall, a decent attachment at best. 7/10 This guide needs to be expanded, feel free to continue it!