Colt Carbine 5.56mm 16" MK4 with 13" Rail and Magpul CTR Stock

The Colt Carbine 5.56mm 16" MK4 is a modern, purpose-built rifle that blends Colt's legacy with contemporary ergonomics and modularity. Built on a 7075-T6 aluminum lower receiver with a direct gas impingement operating system, this 5.56 NATO carbine handles like a refined tool rather than a first-time rifle. The 16.1-inch chrome-lined barrel (1:7 twist, 6 groove) delivers reliable velocity for intermediate-range accuracy and training, while the rifle's 32.5- to 36-inch overall length (adjustable via the Magpul CTR stock) makes it equally at home in tight spaces or behind a barricade. Unloaded weight of 7.3 pounds keeps it manageable in long shooting sessions.

What sets this carbine apart is its out-of-the-box accessory package. The 13-inch Geissele MK4 free-float rail system frees the barrel from the furniture, reducing harmonics and opening the door to optics, lights, and other modern attachments without the cost of aftermarket rails. Magpul MBUS Pro flip-up sights—front and rear (LR adjustable)—provide immediate aiming capability and backup redundancy if your primary optic fails. The four-position CTR stock lets you dial in length of pull, whether you're in gear or running bare; the reversible safety selector accommodates both right- and left-handed shooters without fumbling.

The rifle ships with a 30-round Magpul PMAG magazine, a cable lock, and the manual—everything you need to legally take it to the range or field right away. Semi-automatic fire, single-stage trigger, and the A2 grip round out a no-frills, proven platform. If you want a 5.56 carbine that doesn't demand a decade of tweaking, this Colt walks the line between ready-to-run and genuinely customizable.

Key Features

• 16.1-inch chrome-lined barrel in 1:7 twist for reliable 5.56 NATO performance
• 13-inch Geissele MK4 free-float rail for accessory mounting and improved accuracy
• Magpul MBUS Pro flip-up sights (front and rear LR-adjustable) included
• Magpul CTR 4-position collapsible stock for length-of-pull customization
• Reversible safety selector for ambidextrous operation
• Direct gas impingement system—simple, field-proven, easy to maintain
• Comes with 30-round Magpul PMAG magazine and cable lock
• 7075-T6 aluminum receivers with black hardcoat anodized finish

Specifications

Frequently Asked Questions

What's included in the box with this Colt 5.56 carbine?

You get the rifle, one 30-round Magpul PMAG magazine, a cable lock, and the manual. The Magpul MBUS Pro sights, Geissele MK4 rail, and CTR stock are all factory-installed and ready to use.

Can I add an optic or other accessories to the rail?

Yes. The 13-inch Geissele MK4 free-float rail provides Picatinny mounting surfaces for optics, lights, lasers, and other standard AR accessories. Free-floating the barrel also supports better accuracy if you're running a precision sight picture.

Is this carbine set up for left-handed or right-handed shooters?

The reversible safety selector works for both. However, the charging handle and ejection port are configured for right-hand operation. The Magpul CTR stock adjusts across four positions, so you can customize length of pull regardless of shooting hand.

What's the difference between the Magpul MBUS Pro sights and the CTR stock on this rifle?

The MBUS Pro sights are metal flip-ups that provide backup aiming capability if your optic fails; the rear sight is adjustable for long-range shooting (LR). The CTR stock is a collapsible buttstock that lets you dial in your preferred length of pull across four settings—useful when shooting in tactical gear or with a lighter load.