During the early stages of my law enforcement career, I worked as a uniformed New York State Park Police Officer in the Bronx and carried a Smith & Wesson .38 Special service revolver. Later, working as an investigator for the New York District Attorney's Office, the heaviest firepower I ever carried on duty was a Smith & Wesson nine-shot 9mm Model 39.
It wasn't until I joined the U.S. Customs Service in the early 1980s that I trained with Colt M16 and Colt CAR-15 rifles and carbines. I was issued a brand new Colt CAR-15 with a fixed carry handle and a collapsible stock. I liked this rifle so much that I refused to transition to the Steyr AUG when my agency adopted this 21st century-looking bull-pup design in the tail end of the 20th century.
Even though a considerable number of Steyr AUGs were issued to U.S. Customs Agents I continued to remain a huge fan of the Colt M16, AR-15. and CAR-15-so much so that when I took three undercover boat trips to the coast of Colombia I made sure that my crew was armed with four Colt CAR-15s and one Colt M16 Heavy Barrel, in addition to pistols and shotguns.
I also carried my Colt CAR-15 on numerous air interdiction missions and in the trunk of my government ride in case I needed more firepower while working on land. I liked this rifle so much that I ended up buying a fixed-handle Colt AR-15 A2 with a two-position collapsible stock from a local police supply store when I received written authorization to do so by my agency during the assault weapons ban.
Back then we carried Colt M16 or CAR-15 variants (the CAR-15 was the predecessor to the M4) because at that time no other companies made copies of these famous Colt products. Today, things are different, so much so that I cannot begin to list the number of vendors who manufacture direct impingement and piston version copies of the Colt M16 and M4 Carbine. But Colt is the only manufacturer that produces M4 Carbine variants for the U.S. military. Colt also sells its line of select fire M4s to numerous law enforcement agencies.
The first giant leap into the 21st century as far as law enforcement patrol and tactical rifles occurred when high-quality optics became available for armed professionals who were assigned to tactical duties. Initially, some rifle operators attached optics to various Colt M4s and other copies of this design that had a fixed carry handle. Then someone got the bright idea to kill two birds with one stone and design M16-style rifles and M4-style carbines with a removable carry handle and an accessory rail system on top of the rifle's upper receiver. The accessory rail on top of the upper receiver was designed to accommodate various red dot and magnified optics.
The Colt Model LE6920 is still one heck of a patrol or tactical rifle. Features of the LE6920 include: a four-position collapsible stock, a 5.56mm chamber, a chrome-lined chamber and bore, a barrel with a 1-in-7-inch twist that accommodates ammunition up to 80 grains, an adjustable front sight, a removable carry handle that includes a flip-up iron sight, and an accessory rail under the handle. The Model LE6921 is a semi-automatic version of the LE6920 that is equipped with a 14.5-inch barrel, while the LE6920 is a semi-automatic civilian legal Colt carbine with a 16.1-inch barrel.
From experience I can say that the Colt LE6920 is an outstanding semi-automatic M4-style carbine. If all you need is a patrol rifle that utilizes iron sights or you plan on installing a minimal amount of accessories such as an optic and a tactical flashlight, the LE6920 is well suited to your task. My oldest son who serves as a police officer recently purchased a slightly used Colt LE6920 from one of my shooting buddies so he can carry a high-quality Colt M4-style patrol rifle on duty.[PAGEBREAK]
The Colt LE 6940
One of the main differences between the Colt LE6920 and the Colt LE6940 is the use of a one-piece rock solid upper receiver that has a monolithic rail and a free floating barrel.
In its flat top configuration, the LE6940 is also different from the LE6920 because the LE6940 features folding front and rear sights. The folding front sight is made by Colt, while the rear sight, which can be adjusted to engage targets out to 600 yards, is made by MaTech. This is the same rear sight that is used on all Colt Mil-Spec M4s that are provided to the U.S. Army.
The Colt LE6940 is chambered in 5.56mm and incorporates additional Mil-Spec features in its design. In addition, the Colt LE 6920 and the Colt LE 6940 also have a reversible selector switch. This tidbit of information is important for law enforcement agencies and individual officers who are left handed. While field testing the Colt LE 6940 I found this patrol/tactical carbine to be surprisingly lightweight and easy to carry.
I recently sighted in a sample LE6940 that Colt sent to me to evaluate for this article and found that with some minor adjustments this rifle was dead nuts accurate at 50 yards while using 55-grain Federal FMJ ammunition.
Bear in mind that I intentionally sighted this rifle in while using the folding iron sights that come standard on this carbine. A week later a friend of mine delivered consistent head shot accuracy with every round fired from the 50-yard line while using his brand new Colt LE6940 with an Aimpoint Comp M2 and an Aimpoint 3X Magnifier.
Plain Jane vs. Pimped
Even though I tend to prefer plain Jane M4s, I found myself actually favoring the LE6940 over the LE6920. And the reason for my preference is that the LE6940 is more customizable.
For starters, I can easily install a forward vertical grip and a SureFire tactical light on the LE6940's monolithic rail system. I also have enough room on the rail for a high-quality red dot with or without a 3X Magnifier. I can even turn a Colt LE6940 into a precision rifle by installing a magnified optic like a Trijicon ACOG or a Leupold scope on the rail, which is built into the one-piece upper receiver.
It is important to note that the one-piece upper receiver, which includes the rail, provides an incredibly stable platform that enables the operator of a Colt LE6940 to deliver super accurate shot placement. According to my contact at Colt, who put this in slightly more technical terms, the benefit of a monolithic rail is that "the one-piece upper receiver offers 100-percent zero retention of optics."
The Colt law enforcement carbines are both built to Mil-Spec, and that means something. For an M16 or M4 to be considered 100 percent Mil-Spec, the rifle or carbine must be manufactured to certain government standards with certain high-quality parts and must routinely pass every government inspection and testing procedure dictated by the contract. In fact, only select fire M16s and M4 Carbines that are built to strict government standards can be considered Mil-Spec.
It takes 357 "gages" (testing procedures and inspections) to produce one Mil-Spec select fire Colt M4 Carbine. For example, when Colt builds Mil-Spec barrels and bolt assemblies, it proof tests the rifle barrels with 70,000 psi cartridges followed by magnetic particle inspection (MPI) testing. MPI testing checks for any breakdown in metallurgy, any flaws, deformities, or cracks in steel barrels or their Parkerized coating. Bear in mind that the average 5.56 M855 FMJ round of ammunition has a psi factor of 52,000.
One of the things I really like about Colt law enforcement carbines is that they are manufactured to meet high standards. Quality touches on the Colt law enforcement carbines include having the chamber bored out to reliably feed 5.56 ammunition, a barrel with a 1-and-7 twist, having a properly staked gas key, and an extractor that is designed to have the proper tolerances to ensure reliable operation under extended firing conditions.
A barrel with a 1-in-7-inch twist like the type used in the LE6920 and LE6940 carbines is specifically designed to accommodate and stabilize 5.56 caliber ammunition up to 80 grains in weight. This means that you can engage targets at further distances with greater effectiveness than if you used 62-grain NATO ammunition from a 1-in-9-inch twist barrel.
Nick Jacobellis is a medically retired U.S. Customs Agent and former police officer who was physically disabled in the line of duty while working undercover.