COLT LE901-16S 7.62mm

For the ultimate versatility, Colt’s new 7.62mm LE901-16S accepts 5.56mm…

For the ultimate versatility, Colt’s new 7.62mm LE901-16S accepts 5.56mm uppers like the LE6940CK (below). LE901-16S shown with Leupold 1.1-8×24 Mark 8 scope and Atlas bipod. LE6940CK shown with Vortex Razor red dot.

One of the holy grails of AR manufacturing has been making one lower for both 7.62mm- and 5.56mm-based platforms. For many years, our special operators of every ilk have asked for a “kit” that allows them to change calibers, barrel lengths and sighting systems to adapt to the mission at hand. Most operators have accomplished this so far by using two modular systems—one 5.56mm and one 7.62mm platform—that allow for most of these changes. The ideal, however, would be having the ability to use the same lower receiver for both.

This would have a secondary benefit for the police world. Law enforcement is almost always low on funding. The more an agency can do with less, the better.

Although different missions can require different calibers, it’s rare for an agency to give an operator several weapons. Far too often, the solution is to simply compromise on what officers need. Utilizing one lower receiver for both large and small calibers could be advantageous—a 7.62mm rifle could be issued to an observer on the team, for instance. Given a team’s typical multi-tasking, they could simply swap out uppers to 5.56mm for entry operations or other uses. As a side benefit, those in need of other calibers based on the 5.56mm cartridge, such as 6.8 SPC or 6.5 Grendel, could use the same lower receiver. The concept is valid, but the trick is making it work.

Although similarities certainly exist between the two, upper receivers based on the 7.62mm NATO cartridge require more length. The controls are the same, as is the buffer tube (in most instances), and even trigger mechanisms. Lower receivers on this platform are just housings; the upper receiver deals with chamber pressures and the like. That left adapting the 5.56mm upper to fit the larger lower. There have been several attempts—most were either cost-prohibitive or simply failed to work. I’ve seen plenty of these systems on the drawing board, but many never make it past that stage. It seems one company, Colt, has come up with one successful adaptation—the LE901-16S.

colt-rifle-dnew-le6940ck-rifle
Vltor’s durable IMod buttstock is adjustable, offers storage space, and provides a good cheekweld for use with optics.

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  • jerry simmons

    David,
    New to ar platform, never had a reason too untill now. I am facing a complete right shoulder replacement and am somewhat apprehensive about shooting with my current tradional guns, blr243 which has been at my side forever and a 300wmag that I used for years, problem is they both kick me to the point of tears (really, esp the latter). Now comes the question, I read in this article that you changed uppers to recieve the 6.8 which really holds my interest as shot placement has been going like my eyesight and bones..not good. so the 243 must stay but as a back up. How did you do this and what was the grouping like and recoil. The recoil on the 308AR vs even the 243. I am a real rancher and we have a massive hog problem. Thanks for your input.
    Jerry, jerrye.simmons@gmail.com

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