The Colt LE901 was born out of the Special Operations Command (SOCOM) ‘Special Operations Combat Assault Rifle (SCAR) program that began in 2002. The SCAR program specified a SCAR-L (Light) variant in 5.56mm and a SCAR-H (Heavy) variant in 7.62mm.
The Colt LE901 design enabled the use of both calibers by the end-user by changing upper receiver assemblies. The two images that are attached in this post are from a 2011 marketing sheet promoting the LE901 and it’s multi-caliber capability.
The Colt LE901 design has been modified a few times since 2011 and is no longer in production as a monolithic design. A 7.62mm system
is available in the modernized Colt CM7/M7 rifle design.
The Colt AR-15 Resource 
Always loved the 901, but didn’t have the money back in the day for one of these. Still love quad rails, mlok just doesn’t do it for me. Had to settle for an LMT 16” with quad when I finally had the money. Did eventually fill out my 694x collection at least.
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