The M4 carbine is a gas operated, air cooled, magazine fed, selective fire assault rifle that was derived from the M16 assault rifle. The M4 was used by several military and law enforcement organizations worldwide prior to Judgment Day, and members of the resistance prior to and during the War against the Machines. A variant of the M4, known as the M4A1 offers a different trigger group then the "standard" M4, with the primary difference being the M4A1 has a fully automatic mode, rather than the 3-round burst of the M4.
The M4A1 carbine is an assault rifle variant of the M4 carbine, which itself is a shorter version of the M16 standard assault rifle of the US army. The M4A1 is mostly favored by special operations units. Unlike a standard M4, an M4A1 has a fully automatic fire option.
Terminator 3: Rise of the Machines
Terminator: The Sarah Connor Chronicles
Cameron used an M4A1 while checking the perimeter of the safe house after Wells circumvented security and smashed through the living room door. Sarah Connor later acquired one at the Serrano Point Nuclear Power Plant to combat the Greenway Terminator.
The "standard" M4 carbine was used by at least one prison guard at the Los Angeles County Jail.
- Terminator 3: Rise of the Machines
- Terminator Salvation
- Terminator: The Sarah Connor Chronicles