The M4A1 is handy, powerful and easily modifiable. However the weapon is not without flaws. The short 370mm barrel limits the muzzle velocity of the 5.56mm bullet, decreasing effective range and reducing the chance of bullet fragmentation (the primary method of incapacitating targets with the 5.56mm NATO round). The barrel and forend tend to overheat if fired too rapidly. The shortened gas system causes a higher rate of fire than the M16, with greater stress on moving parts.
The M4A1 is equipped with a 30 round magazine and has a rate of fire between 700 and 950 rounds per minute. The maximum effective range is about 360 metres.