Colt M4 Le6940 Upper Group 16In W/ Bcg And Sights

The Colt M4 LE6940 upper group with 16-inch barrel, BCG, and sights brings modern rifle architecture to your AR platform build. This complete upper receiver assembly combines a monolithic design with a free-floated barrel, giving you the rigid mounting platform and accuracy potential serious shooters expect. Whether you're assembling a dedicated carbine for duty, competition, or tactical training, the LE6940 delivers the kind of quality control Colt's known for—chrome-lined barrel, 1-in-7 twist, and button-rifled construction all in one package.

The monolithic upper receiver is the standout feature here. Instead of a traditional flat-top with a separate rail system, you get a one-piece Picatinny rail milled directly into the receiver. That means zero flex, zero compatibility headaches, and maximum rigidity for optics and accessories. The free-floated barrel isolates performance from the upper so nothing interferes with accuracy. Built-in flip-up front sight gives you a backup aiming solution right out of the box—compatible with standard height rear sights so you can keep existing backup iron sights or run optics only.

This upper group ships complete with bolt carrier group (BCG) and both front and rear backup sights, so you have everything needed to mate to a compatible lower receiver and start shooting. The 16-inch barrel length keeps overall handling manageable while offering a good velocity and sight radius balance for general-purpose rifle work. Standard NFA rules apply as always.

Key Features

• Monolithic upper receiver with integrated one-piece Picatinny rail
• Free-floated barrel for improved accuracy and consistency
• Chrome-lined 16-inch barrel with 1-in-7 twist, button-rifled
• Includes bolt carrier group, front and rear flip-up sights
• Built-in flip-up front sight compatible with standard rear sights
• Rigid mounting surfaces throughout

Specifications

Frequently Asked Questions

What lower receiver is this compatible with?

The LE6940 upper group is a standard AR-15 upper and will mate with any AR-15 compatible lower receiver. Make sure your lower is properly registered per NFA rules if applicable.

Does this come with everything I need to build a complete rifle?

This upper group includes the BCG and backup sights, but you'll need to source a compatible lower receiver, furniture, and any other components to complete an AR build.

What's the advantage of the monolithic upper receiver?

The one-piece design eliminates the seam between a traditional flat-top and rail system, providing a more rigid, unified platform for mounting optics and accessories with zero movement or flex.

Can I use this with a standard rear sight?

Yes. The built-in flip-up front sight is compatible with most standard height rear sights, giving you flexibility in backup iron sight setup or allowing optics-only mounting if you prefer.