M4A1

The M4A1 carbine is a fully automatic variant of the basic M4 carbine intended for special operations use. The M4A1 has a "S-1-F" (safe/semi-automatic/fully automatic) trigger group. The M4A1 is used by almost all U.S special operation units including, but not limited to, Marine Force Recon, Army Rangers, Army Special Forces, Navy SEALs, United States Air Force Pararescue and Air Force Combat Control Teams. The M4A1 is especially favored by counter-terrorist and special forces units for close quarters combat and urban warfare because of the carbine's compact firepower. It has a maximum effective range of about 500 to 600 meters (550–660 yd). The fully automatic trigger gives a more consistent trigger pull, which leads to better accuracy.

In-game
It is effective in medium-long range. It uses 30-round mags and can use 20-round mags, has good recoil and accuracy. It supports attachments also.