Fan of the M4A1 and M4? So is the U.S. Army. More of the popular weapons will be making their way into the hands of troops.

The Army has ordered $212 million worth of M4 and M4A1 carbines from Colt Defense and FN America.

M4

A classic, the M4 combines lightweight mobility with effective firepower. The 5.56-mm carbine was designed to meet the U.S. military’s high performance standards. 

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It’s got a 14 and a half-inch barrel and with the stock extended the weapon is 33 inches long. The rate of fire is 700 to 950 RPM and the M4 has an effective range of about 600 meters, or 1,969 feet.

In 2013, the military placed a $77 million order with FN for 120,000 M4s. Attempts to replace the popular M4 with another weapon, however, have not been successful. Instead, the weapon has been improved through programs like M4s to M4A1s and the M4A1+ initiative.

M4A1

The M4A1 has been popular with special operations warriors for about two decades.

Last year, the Army began modifying nearly half a million M4s to upgrade them to M4A1s. And these M4A1 carbine rifles have been rolling out in stages to soldiers. The Army is expected to finish the conversion of M4s to M4A1s by 2020.

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The conversions mean that the M4A1s weigh a bit more, but once modified they can offer a lot of advantages, such as in suppressing fire.

The barrel is heavier by a few ounces, but it provides better resistance to heat and it enables shooting longer strings of fire with accuracy.

The conversion also includes a shift from three-round burst to fully automatic. And good news for lefties, this version provides ambidextrous safety controls.

M4A1+

The M4A1+ program aims to further enhance the weapon.

The "plus" in M4A1 includes changes like an extended 12-inch forward Picatinny rail. This lets soldiers attach more accessory advantages like laser sights, optics, lights and pointers. The front and rear iron sights will be removable.

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M4A1+ is meant to have better accuracy - no farther than five inches from the target at 300 meters, or 984 feet, throughout the life of the barrel. The shift to a floating barrel will help to improve accuracy.

An advanced flash suppressor reduces firing signatures during both night and day missions. The “plus” also provides an optional sniper-style single-stage trigger.

The contract to supply the new M4s and M4A1s runs through 2020. The Army also recently ordered $84 million worth of M240 machine guns from FN America.

Shopping for a Colt?

For consumers, from now through Dec. 31, Colt is offering purchasers of a new Government Model or Defender pistol a free Colt Carry Kit. The kit includes one hundred dollars worth of Blade-Tech holster, additional magazine, and cap.

 Ballet dancer turned defense specialist Allison Barrie has traveled around the world covering the military, terrorism, weapons advancements and life on the front line. You can reach her at wargames@foxnews.com or follow her on Twitter @Allison_Barrie.

Allison Barrie consults at the highest levels of defense, has travelled to more than 70 countries, is a lawyer with four postgraduate degrees and now the author of the new book "Future Weapons: Access Granted"  covering invisible tanks through to thought-controlled fighter jets. You can click here for more information on FOX Firepower columnist and host Allison Barrie and you can follow her on Twitter @allison_barrie.