The Colt Firearms M4 FPB (LE6920-FBP2) is a direct impingement semi-automatic rifle chambered in 5.56 NATO / .223 Remington. It has a 16.1-inch barrel with a 1:7" twist rate made from 4150 CMV steel, 30-round capacity, and weighs 7.3 lbs unloaded. Finish is black anodized. The stock is a Magpul CTR 4-position adjustable. Sights are Magpul MBUS Pro steel flip-up front and rear. The safety selector is reversible for ambidextrous use. 
 

Key Specifications 

• Caliber: 5.56 NATO / .223 Remington 
• Barrel Length: 16.1 inches 
• Barrel Twist: 1:7" 
• Barrel Material: 4150 CMV steel 
• Capacity: 30 rounds 
• Weight: 7.3 lbs (unloaded) 
• Finish Color: Black (Anodized) 
• Model Number: LE6920-FBP2 
   

Detailed Features 

 
The 4150 CMV barrel with 1:7" twist handles heavier 77-grain projectiles well, which is an advantage for longer-range accuracy over the more common 1:9" barrels. The reversible safety selector accommodates left-handed shooters without a parts swap. The Magpul CTR stock has four length-of-pull positions and is more stable than mil-spec stocks due to its locking mechanism. Magpul MBUS Pro sights are steel rather than polymer, which holds up better to hard use.

The Colt M4 FPB draws buyers who specifically want Colt's manufacturing standards on an M4-pattern carbine with upgraded furniture from the factory. Build quality and reliability are consistently praised. The Colt name carries weight with buyers who prioritize American manufacturing and mil-spec tolerances.

Reliability feedback is positive across a range of ammunition types. Accuracy at typical carbine distances is well-regarded, with the 1:7" twist and 4150 CMV barrel getting specific mention from shooters who run heavier loads.

Ergonomics get good marks. The Magpul CTR stock is appreciated over standard mil-spec stocks. Controls are intuitive and the overall handling is comfortable for extended sessions.

Price is the main criticism. The M4 FPB costs more than comparable AR-pattern rifles from other manufacturers. Some users feel the Colt premium is fully justified; others note that similar specifications are available at lower prices from brands like Smith & Wesson or Anderson. Customization discussions are common. The platform accepts a wide range of aftermarket components, which owners appreciate.