This is a review of the Colt Modular Rifle LE901-16S. Although very late in the game, Colt has finally released a 7.62mm caliber rifle. The concept of this rifle is multi caliber but in a very different way than its been done in the past. The rifle is convertible from the standard 7.62mm upper receiver to the standard mil-spec M16/M4 upper receiver with the use of a magazine well adaptor. From my perspective, this is an excellent 7.62mm assault rifle. Although a good selling point to be convertible the reality is if you want a 5.56mm base rifle you would have a dedicated rifle for it. A solider is not going to carry a spare upper receiver assembly, buffer assembly and magazines in his backpack. This rifle in its 7.62 configuration would certainly have been an excellent assault rifle for use in Iraq and Afghanistan due to the longer shot range opportunities, as well as its barrier penetration performance. The success of this rifle has been minimal, not due to the design, but due to the fact that its competing against rifles such as: HK417, SCAR17, Knights Armament SR25 rifles, and LMT MWS series rifles, which already have several years of successful combat experience.