M4 Custom



The M4 Custom is an in-game take on the the M4A1, a highly modifiable carbine based on the M16 rifle primarily used by the US military. Introduced in 1994 as a complement for that firearm, the M4 was designed as an ideal rifle for CQC/CQB (close quarters battle), and was also made to be extremely modular with additional accessories; due to this factor and ever-increasing use for the size and maneuverability advantage, it has displaced the M16 with many US military units, although in-game by 2014 the XM8 is used by Rat Patrol Team 01, the Army/Marine team at the Volta River, and later the troops onboard USS Missouri.

The in-game M4 Custom appears with a backup iron sight (BUIS) and a 'clean' optics-mounting rail atop the upper receiver with no carrying handle, with a free-floating rail attachment system (RAS) with rails on all four sides; it also has a tan/khaki-colored pistol grip, and buttstock. Old Snake always uses the charging handle behind the BUIS to chamber new rounds, even though pressing the bolt release (the vertical button on the left side of the weapon) would perform the same function more quickly. This could be explained by the fact that some shooting schools believe that using the charging handle instead of the bolt release is more reliable (while technically unproven).

In Metal Gear Solid 4, the M4 Custom is one of the most flexible weapons in the game, with five attachment-mounting points that can be used to maximize its utility; this distinguishes it from the laser-sighted M4 used in the Big Shell. It is a CQC-capable weapon, albeit like other CQC-capable long guns it has limited functions, primarily the throwdown and the disarm. Unlike standard-issue "M4", it has both 3-round burst and fully automatic firing modes in addition to semi-automatic fire. (There's a few AR-15 variants that uses four firing positions, like some Navy M16A3 or the so-called "M4 Commando enhanced" http://autoweapons.com/photos05/apr/995m16.html)

The M4 Custom first appeared when Drebin gave it to Old Snake as an introductory 'gift,' although it wasn't laundered and therefore Drebin had to give him the "new generation nanomachines" in order for it to work. In South America, Snake managed to get a clean headshot on Vamp using the M4 Custom, then briefly shot it out with the soldiers accompanying Vamp and Naomi before they were picked up by Drebin. The M4 Custom was last seen in Outer Haven, where as Snake started to have seizures, he dropped the M4 Custom on the floor. Despite it (along with any other weapons) being unusable in the subsequent area, he is seen afterward fending off Scarabs with it so that Metal Gear Mk. III could upload FOXALIVE into GW.

During the early render of MGS4, heavily customized M4 Customs acted as the standard issue weapon for most PMC soldiers as trailers and pictures can be seen with soldiers using them against Militiamen and Snake. The idea of the M4A1 being standard issue to the PMCs was later phased out in favor of the Mk.17 SCAR-Heavy during the latter stages of development. The pictures of the PMCs using M4A1s can be seen in Act 1's briefing session where Campbell shows a few pictures in a slideshow while explaining the rapid growth of the PMCs. Drebin also described the M4 Custom to be one of the most favored weapons by the PMCs even though it is clear they are not seen being used in-game.

Components
In its basic form, several of the M4 Custom's components are easily identifiable aftermarket items:


 * A.R.M.S., Inc. #40L Low Profile Rear Sight
 * Knight's Armament Co. M4 Carbine R.A.S. Free Float Rail System
 * Precision Reflex, Inc. (PRI) Flip Up Front Sight
 * Troy Industries, Inc. 5.56mm Medieval Muzzle Brake (Old version, circa 2005)

Other components, such as the flattop (railed) upper receiver, the lower receiver, the 14.5 inch barrel with an M203 notch, a tritium night sight embedded in the front sight post (visible as a white dot), and the A2 grip and six-position collapsible buttstock colored in coyote tan, are too generic to identify them as specific items from specific manufacturers.