Colt 933
The Colt 933 is a compact carbine based on the AR-15, M16 rifle and M4 Carbine produced by Colt starting in 1995. Due to its compact size, the short-barreled Colt 933 continues to be used by various US Special Forces and by some foreign forces, including Israeli Special Forces. History

During the Vietnam War, Colt would issue a carbine variant of the M16 known as the XM177, for close quarters combat. These rifles would have the barrel length cut down to 10 inches (25 cm) which upset the ballistics, reduced its range and accuracy, and had considerable muzzle flash and blast. Colt would partially fix this by adding large flash suppressor, although it did not help how loud the rifle was. Colt would later lengthen the barrel from 10 inches to 11.5 Inches in response to field testing and would be adopted as the XM177E2, which would be assigned to MACV-SOG units. This reduced the muzzle flash and blast issues that the 10 inch XM177E1 had and would be produced until 1970. After Vietnam, Colt would mainly focus its attention to the carbines with 14.5-inch (370 mm) barrels and the rifles with 20-inch (510 mm) barrels but continue to make carbines with 11.5-inch (290 mm) barrels, which they call Commandos. The first of which was the Colt 733, which was created from whatever spare parts Colt had lying around. These became popular with police and special forces users such as Delta Force and USMC Force Recon. In 1995, Colt would introduce the 933 as the M16A2 Commando, after the success of the M4 Carbine. These modernized Commandos have a "flattop" receiver, with a removable carry handle and a MIL-STD-1913 Picatinny rail, with semi-automatic and automatic fire. The parts are also interchangeable with the longer M4 Carbine. Despite suffering from some of the same issues that plagued the earlier Commando  carbines, the 933 still remains popular amongst some police and special forces users. Colt would later  rebrand the 933 as the M4 Commando. Users 
 
 : Used by SAJ. : Used by LAPD Metropolitan Division SWAT and USMC Force Recon. References

Assault rifles of the United States
Carbines
Colt rifles