The M4 is a well-rounded weapon with decent handling, above-average damage, and adaquate rate of fire. Its first-shot recoil is noticeable, so the Flash Hider attachment is recommended over the Compensator. That being said, it is still suitable for mid-range engagements.
The weapon is generically designated as an 'M4', which is the burst-fire specific version of the gun, which has only 2 firing modes, semi-auto and 3-round burst. The later M4A1 is the correct designation for this weapon due to its ability to fire full-auto. With that said, either version of the weapon shouldn't have the option of both 3-round burst and full auto firing modes, however the Colt "M4 Enhanced" Models (RO-738, 778, 938, & 978) have this trigger group that includes both three round burst and fully automatic included.
This M4 has a custom trigger group which is capable of both three-round burst and fully-automatic, alongside semi-automatic fire, which has only been present in the M16A2 assault rifle as far as AR platform military rifles go.
There is no gas block on the M4's model, which means that in reality, the rifle would not be able to automatically cycle after each shot.
The M4 is based on a customized M4A1 Block II rifle with a Daniel Defense MK18 RIS II railed handguard and a Command Arms UMPG16 pistol grip.