The M4 Pistol is a family of American-made semi-automatic handguns chambered for 9mm ammunition. Various incarnations of the weapon have been employed by the United States Colonial Marine Corps as their standard issue sidearm over several decades. The M4 is an update version of the Colt M1911 pistol designed by John Browning over 200 years earlier.
The M4 is a 9mm automatic, recoil operated, magazine-fed handgun. The working mechanism is made of steel alloy with some high-strength plastic parts, while the outer casing is machined from lightweight alloys. The entire weapon, including a full 12 round magazine, weighs no more than 0.95 kg.
9mm Ball: The M4's standard ammunition is a 126 grain 9mm ball rimless straight round. Although adequate against soft targets, this round has very poor armor penetration characteristics even at close range, leading to the introduction of the M901 round (see below).
M901: A new armor-piercing cartridge being introduced to replace the standard ammunition for the M4, the M901 consists of a subcaliber metal core encased in a high-impact resin bullet. Upon impact, the resin case breaks apart, allowing the core to penetrate the target's armor.
- Main article: M4A3 Service Pistol
The M4A3 pistol is a replacement for the ageing Heckler & Koch VP70 in service with the USCM. While sufficiently powerful to be effective against most unarmored foes, it lacks effectiveness against tougher targets with heavy armor, such as Predators and Xenoborgs.
The M4A4 is an upgrade over the M4A3, trading the 9mm round for a .45 caliber cartridge, granting it increased power at the cost of a slightly smaller magazine capacity. A greater range of ammunition types are also available, including expanding anti-personnel "dumdum" rounds and tungsten core armor-piercing rounds.
In the Gold Edition and Classic 2000 versions of Aliens versus Predator, the M4A3 is standard issue for the USCM. It is powerful against Warriors and served as a reliable backup for the Pulse Rifle in the early stages of the game. However, it was ineffective against stronger enemies and Xenomorph castes and was little use against other human combatants. The game also features dual M4A3s, which doubled the rate of fire and magazine capacity, but at the cost of a longer reload time. Note that the pistol does not appear in the original version of the game.
In Aliens versus Predator 2, the M4A4 pistol is quite effective, able to take down a Drone in 2-3 shots, and a Runner in fewer still. But where the weapon truly shines is in its armor-piercing ammunition, which makes it a great weapon for defeating the hard exoskeleton of a Praetorian or the body armor worn by the Iron Bears. Unfortunately, armor-piercing ammunition is exceptionally rare.
In Aliens versus Predator 2: Primal Hunt, the M4A4 returns, this time able to be dual-wielded.
In Aliens versus Predator: Extinction, the M4A3 pistol is the standard issue weapon for Medics and base grade Synthetics. Overall it is weak and ineffective against all but the most basic of enemies, most useful only when used to finish off Chestbursters or wounded Warriors.
In Aliens: Colonial Marines, the M4 appears as the Armat M4A3 Service Pistol. In the game the handgun can be upgraded with several attachments and can alternatively fire armor-piercing ammunition. A "Legendary" version supposedly belonging to Private Vasquez also appears under the name Vasquez's Pistol.
- Visually, the M4 Pistol is based on the Colt M1911.
- Concept art for Aliens: Colonial Marines reveals that the M4A3 seen in the game was originally going to be a somewhat antique (by the time of the game) Colt M1911.
- Vasquez's Pistol is based on the M4 (and therefore the M1911), even though Vasquez's sidearm in Aliens was actually a Smith & Wesson Model 39 and not an M1911.