La France M16K The La France M16K is a M16 rifle modified by the company La France Specialties , which among with other firearm - related activities , convert common military weapons into more compact configurations typically for law enforcement and special forces use . The M - 16K was designed by Timothy F . La France , the principal of La France Specialties , formerly of San Diego , California , for use by persons anticipating ambush while in transit . Its short length and unique sighting system was designed to facilitate firing from moving vehicles , where the extra length of even a CAR - 15 or XM - 177 might create a problem . Its extremely compact envelope also makes it an ideal weapon for helicopter crews , who otherwise would be forced to rely on sidearms for protection in the event of a forced landing . Design . The M16K is a so - called " K " weapon ( " K " standing for the German word Kurz meaning short ) . The La France M16K , was basically a standard military M16 rifle , chambered for the standard issue 5 . 56 mm cartridge with an 8 3 / 8 inch ( 213 mm ) barrel . The standard barrel length is 20 inches ( 508 mm ) . Like many automatic and semi - automatic weapons the M16 utilizes pressure from the propellant gases in the barrel to cycle the bolt of the firearm . Most automatic weapons use a mechanical device such as a rod and piston between the bolt and the propellant gases . This is not the case in the M16 design in which gases are tapped off the barrel near the muzzle and flow though a tube to directly impinge on the bolt to initiate the auto loading cycle . In a standard issue M16 , the gas tube is roughly 16 inches ( 406 mm ) long to produce an automatic ( cyclic ) rate of fire of approximately 650 rounds per minute . Shortening the barrel increases the rate of fire significantly and thereby makes the weapon difficult to control and less reliable . To use a significantly shorter barrel than the standard issue without increasing the rate of fire , La France designed ( and subsequently patented ) an adjustable gas system that would keep the rate of fire the same as with a full - length barrel . History . The M16K was produced by La France beginning in 1982 , subsequently a highly modified variation of this gun was developed which was designated the M16K - 45 which was chambered for the . 45 ACP round and utilizing 20 or 30 round Thompson submachine gun magazines . Except for the magazines this firearm was entirely manufactured by La France and not just a modification of an existing firearm as was case with the original M16K . In the 1990s agreement was entered into between La France Specialties and NAIT to distribute La France Specialty products . La France Specialties was acquired by Surefire , LLC in 2004 , and all La France products are still available . The M - 16K uses the early Colt AR - 15 upper receiver , and therefore lacks the forward assist and shell deflector found on A1 and later upper receivers . The rear sight consists of a metal tube welded onto the carrying handle in place of the original adjustable sight , creating a quasi - ghost ring sight . The handguards are shortened versions of the original triangular handguards . M - 16Ks make use of the stainless steel twin - tube La France gas system , which greatly increases reliability using the short barrel . The lower receiver is a standard M - 16 select fire unit . M - 16Ks are quite rare and very collectible . The later M - 16K . 45 variant was produced using proprietary upper and lower receivers designed by Timothy F . La France specifically for the . 45 ACP round . Both are forgings . The M - 16K 45 was produced in both a fully automatic Title II version with a short barrel and a semi - automatic version fitted with a 16 " barrel to allow it to be sold as a Title I firearm . The barrels are compensated to reduce muzzle climb in fully automatic fire . Production delays resulted in the semi - automatic version not being ready for civilian sales until after enactment of the Federal Assault Weapons Ban in 1994 , which impaired sales . When the Federal Assault Weapons Ban lapsed , M - 16K 45s again became legal for sale . Fully automatic and semi - automatic versions of the M - 16K . 45 may be obtained from North American Integrated Technologies ( NAIT ) in Texas , which provided the funding for development , testing and production of the M - 16K . 45 variant . The fully automatic versions are post - May 1986 machine guns , and may only be transferred to available to persons and agencies permitted to have post - May 1986 machine guns under the National Firearms Act . The semi - automatic versions are available for civilian purchase to qualified buyers . Accessories . The LaFrance M4 HFZ Suppressor unit is designed to work with short - barreled rifles like the LaFrance M16K for use in semi - automatic as well as full - automatic fire mode .