E&C XM177E2E&C's take on the M4's grand daddy, this XM177E2 features a metal receiver, buffer tube and barrel, but remains extremely lightweight due to its plastic furniture. This gun also features E&C's quick change gearbox, allowing you to swap your spring in less than 10 minutes, without having to pull your gearbox out of the gun. Despite the pictures, this rifle has complete COLT style trades from the era.