In this article, first, I want to talk to you about the M4A1 and what makes it our bread and butter choice across special operations teams. I will discuss the good and the bad, and why I think it’s here to stay.


M4 Carbine Firing

The M4A1 carbine entered service in 1994, taking feedback from lessons-learned in the Gulf War where the M16 series was dominant. A lot of troops were asking for a shorter weapon for a variety of reasons such as urban operations, vehicle crews, and special operators to name a few. With advancing technologies in optics and laser systems, there was a desire to produce a more effective and modular weapon, and that’s where the M4 platform excelled with the introduction of the Special Operations Peculiar Modification (SOPMOD) Program  which had been growing since the late 80’s and began production in 1992.

M4 Carbine SOPMOD Kit

I want to focus this article on the M4A1 since that’s the go-to choice of special operations. It differs from the M4 in having a full-automatic fire mode instead of a 3 round burst. Full-auto is nice to have and the trigger feels a lot better than a burst trigger. The standard M4A1 carbine has a handguard with double heat shields to better protect the user’s hands from the barrel heating up rapidly in automatic fire and the barrel has also been thickened to better dissipate heat. It should be noted that the Army plans to expand the M4A1 issuance to more units. The basic specifications are as follows:

  • Weight, unloaded/loaded:  6lb 7oz / 7lb 6oz
  • Length, extended/closed buttstock:  33in / 29.75in Barrel:  14.5in length, 1:7 right-hand twist
  • Rate of Fire:  700-950rpm cyclic, 45rpm semi-auto, 12-15rpm sustained
  • Muzzle Velocity:  2,900ft/sec (884m/sec)

M4A1 Left Side

The CQBR Upper Receiver is a drop in replacement for the M4A1 standard upper receiver and when installed is known as the Mk18 by type-designation. It was originally intended to replace the 9mm MP5 series of sub-machine guns with a weapon firing the common 5.56mm round capable of penetrating body armor, while still making use of SOPMOD accessories. As such, it is very effective in Close Quarters Battle (CQB) environments.

M4A1 Right Side