Caliber - 5.56mm NATO (.223 Rem)
Capacity - 20 or 30-round magazines
Action - Gas-operated semi-automatic
Barrel - 16 inches
Weight - 8.32 lbs. w/ empty magazine

The M4 concept began life in the mid-1980s as a request from the United Arab Emirates for a 5.56mm carbine. The design specs were later adopted by the US Military to supplement its M-16A2s. The 11.5" CAR-15 had been well received in Vietnam, but had several shortcomings in the accuracy and reliability departments. The Colt company's answer was built around a new 14.5" barrel and 4-position telescoping stock, and incorporating the improvements made to the M-16A2 - better sights, receiver reinforcements, new handguards and flash-hider. The resulting weapon was type-classified as "M4", making it the first true carbine adopted by the US military since the M1, M2 and M3 carbines of WWII. Currently, this weapon is in service in two forms: the basic M4 features a flat-top upper with removable carrying handle, safe-semi-burst trigger group and double-shield handguards. It is in service with regular units of the US Army and Marines. The M4A1 or "SOPMOD M4" is the Special Forces version, which features a flat-top upper with detatchable carrying handle, safe-semi-auto trigger group, and modular Knight rail system handguards. For additional information and pictures, visit and the Wikipedia M4 Carbine Page.

In recent years, the M4 configuration has gained popularity among civilian shooters and collectors. As a result, most major AR-15 manufacturers have started offering M4-pattern weapons, upper assemblies and barrels. Purists would argue that certain features and markings found on the M4 are Colt trademarks, and so the only true M4s are Colts. They have dubbed non-Colt M4-type weapons as "M4geries" (M4 forgeries). They are correct to an extent, as Colt has trademarked certain features and is the sole government supplier for the M4 until their contract expires in 2011. However, I would argue that if it looks like a duck, walks like a duck, and quacks like a duck, it's a duck. Thus, I will refer to any weapon with the general characteristics of an M4 as an "M4" or "M4-type", even though it might not be a Colt weapon.

The Build
With the expiration of the onerous "Assault Weapons Ban" in 2004, it once again became legal to add certain features, such as adjustable stocks, threaded muzzles and flash hiders, to domestically produced semi-automatic rifles. That being the case, I removed the now-unnecessary ban-compliant stock and upper receiver assembly from my M4 and sold them, in order to rebuild the gun in a more functional and aesthetically correct "no ban" configuration.

To my veteran Bushmaster lower with RRA 2-stage trigger, I added a 5-position VLTOR Modstock with an extra-heavy 9mm buffer inside. I mated this with a complete Stag Arms barreled upper from Bravo Company. As part of Stag's "Military Ops Series", this upper includes such features as: flat-top receiver with laser-etched rail address numbers; 16", chrome-lined, 1x7 twist M4-profile barrel with extended feed ramps; and a Teflon-over-hard-anodized finish. Inside is a mil-spec CMT bolt group, and the charging handle includes the nifty PRI "Big Latch" for easier manipulation. Up front, I installed the outstanding Samson MRFS-C rail system. This three-piece system free-floats the barrel for optimum accuracy, but does not require removal of the barrel or front sight base for installation. Rounding out the build are a TangoDown vertical grip, Surefire light, Magpul rail covers, an Aimpoint COMP-ML2 red-dot in a LaRue LT-150 mount, and an ARMS #40 back-up iron sight.

The rebuilt M4 received its baptism by fire at the DETC Carbine I/II Course in Racine, WI. The new upper had about 200 rounds on it going in, and I fired another 650 or so through it during the course. The gun had been cleaned and lubricated prior to the start of class, but received no further cleaning or maintenance during the entire two days of shooting. It performed admirably; reliability was 100% save for a misfeed caused by a faulty magazine which was quickly identified and discarded - and it proved accurate enough to hit torso-sized steel plates out to 300 yards!

The Bottom Line
I like the M4 pattern carbines. They're somewhat of a fashion statement in the world of AR's, but they are also eminently practical. I appreciate the lighter weight and quick pointing characteristics of the M4-profile barrel, and the VLTOR stock is sturdier and more comfortable than the standard fixed or collapsible stocks. The flat-top upper and rail system forearm provide improved cooling and give a multitude of optics and accessory mounting options, though I prefer to keep mine relatively uncluttered. Maneuverable and handy, but still accurate and hard-hitting - the M4 is equally well suited to the needs of Special Forces personnel and armed citizens!

Update 5/2/07 I have started a performance log on the M4 Carbine, and will provide periodic updates on round count, reliability, parts breakage/replacement and other statistics. Stay tuned!

M4 - Homeland Security Rifle!

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