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March 13, 2012
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Richard Fairburn Law Enforcement Firearms
with Richard Fairburn

Colt: The legend lives on... in the Colt M4 Advanced Law Enforcement Carbine

Part Two: After reviewing the Colt M4 Advanced Law Enforcement Carbine, I gave Colt a credit card number instead of returning the test rifle

As I said in my column yesterday on the 1911 “Rail” Gun, I do not own stock in Colt Manufacturing, nor is the company paying me to write this review.  However, I plead guilty to being a life-long admirer of all things Colt.  Amazingly, in just one generation, Colt’s contribution to two military and police success stories has almost faded from police officer’s memories, the 1911-pattern .45 semi-auto pistol and the AR15/M16 series of rifles.  When I started in Law Enforcement, if you wanted a .45 or an AR15, it would be a Colt — nobody else made them.  Nowadays, Colt is almost the last brand name many police officers think of for these weapon platforms, but Colt wants to change that.

A few months ago I received an email from Colt’s marketing representatives asking if I would be willing to review some Colt products to help them re-establish their standing in the LE marketplace. 

Would I?  Hell, Yes!  Colt has gone through several boom and bust cycles in their marketing and business enterprises, but the quality of their production has never faltered.  Most gunsmiths will tell you a Colt AR rifle or 1911 pistol is still the standard by which all other brands are judged. 

The M4 Advanced Law Enforcement Carbine
The first Colt test weapon I received was an M4 Sporter, their Advanced Law Enforcement Carbine — catalog #SP6940 — with a monolithic upper receiver that blends into a quad-rail configuration.  The monolithic receiver allows for a fully free-floated barrel, in this case a 16-inch chrome-lined version in the M4 configuration.  A monolithic receiver adds two big advantages, in my opinion:

a rock-solid mounting system for optics and accessories
a free-floated barrel, to enhance accuracy

Unlike other monolithic carbines I have handled, the Colt is not much heavier than a model with removable hand guards, weighing 6.8 pounds empty.  I have a pet peeve about unnecessarily heavy AR carbines, especially when officers screw on “tacticool” gadgets which get in the way and add to the overall weight.  The 6940 meets my personal weight criteria for a patrol rifle, staying under nine pounds fully loaded and ready to go.  To my notion, ready-to-go means a carbine fitted with a tactical sling, 1x optical sight, flashlight/mount and a loaded 30 round magazine.

Many newer AR systems have replaced the original direct gas impingement operating system with a gas-operated piston.  A piston system is unquestionably more reliable in the fine sand our troops face in Afghanistan and Iraq.  But, for LE use, I feel the original gas system is perfectly reliable and much less expensive.  Colt has built piston-driven variations of the Armalite design for decades.  If you want one, Colt’s piston variation of this test rifle, the SP6940P, adds more than $600 to the retail price.

For accuracy testing, I mounted a 4x scope on the 6940 carbine and fired three-round benchrest groups at 100 yards.  My choice of a 4x magnification optic was to simulate the carbine’s potential use as a mid-range Designated Marksman rifle.  For more than 20 years, I have tested accuracy in any .223/5.56mm caliber weapon using Black Hills Ammunition’s 52 grain Open Tip Match (OTM) load.  Though the bullet is much too fragile for duty use, no other load I’ve tried can compare to the Black Hills 52gr for consistent accuracy in all barrels — fast twist or slow twist. 

Jeff Hoffman, the honcho at Black Hills Ammo, recently sent me some of his military-contract 5.56mm Mk262 Mod 1 ammunition (77 grain OTM), claiming it was slightly more accurate than the 52 grain load — only in fast-twist barrels, of course.  From this Colt carbine, the two loads were a statistical tie for accuracy, with three-shot groups hovering around ½ inch center-to-center at 100 yards.  This mil-spec 16-inch carbine produced ½ MOA accuracy using a 4x optic, despite having to fight my way through a 7+ pound mil-spec trigger with a huge amount of gritty creep before the let off.  With a match-grade trigger and sniper-grade 10x optics, this Colt carbine should approach ¼ MOA accuracy, rivaling my .223 bolt-action sniper rifle.

Another feature on the test carbine is the new Rogers “Super Stock.”  This collapsible four-position stock has a separate locking lever that eliminates the “woogedy” nature of this breed of stock.  To become a perfect patrol rifle, this carbine needs only a quality 1x optical sight, a flashlight and a better trigger.  Many after-market match trigger systems use a lighter hammer and springs, which might not reliably fire the harder primers used in 5.56mm mil-spec ammunition, so be careful which one you choose.  The MSRP for the SP6940 carbine is $1,500, comparable with other brands when they are similarly equipped. 

In the interest of honestly, I must admit I gave Colt a credit card number instead of returning the test rifle... it’s that smooth and accurate!  I plan to equip this super-accurate little carbine as a Police Designated Marksman (PDM) carbine, so it will get a Geissele SSA two-stage trigger and a low-power variable scope. 

Look for a future examination of the PDM concept.  Speaking of looking around, yesterday my review of the 1911 “Rail” Gun was posted to PoliceOne.  If you haven’t yet seen it, maybe you might check that out as well. 

About the author

Dick Fairburn has more than 30 years of law enforcement experience in both Illinois and Wyoming, working patrol, investigations and administrative assignments. Dick has also served as a Criminal Intelligence Analyst and as the Section Chief of a major academy's Firearms Training Unit and Critical Incident training program. He has a B.S. in Law Enforcement Administration from Western Illinois University and was the Valedictorian of his recruit class at the Illinois State Police Academy. He has published more than 100 feature articles and two books: Police Rifles and Building a Better Gunfighter.

Contact Richard Fairburn



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