| The M4 is a carbine version of the basic M16 assault rifle in use by the US military. The weapon is equipped with a shorter barrel and a telescoping, four position buttstock. The modifications allow for a more manoeuvrable weapon, being lighter and shorter than the basic M16. The US SOCOM (Special Operations Command) modified the M4 into the M4A1 configuration, consisting of a flat top receiver with integral accessory rail instead of a permanently attached carrying handle. The trigger unit is also modified to allow for full automatic fire rather than three round bursts. The SOPMOD (Special Operations Peculiar Modification) kit in use on this 3D model consists of the M4A1 carbine equipped with the RIS (Rail Interface System) instead of standard handguards. This allows the attachment of various accessories such as laser pointers, various optical sights, tactical lights, forward handgrips or the M203 grenade launcher. 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. | 
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