M16 Upper Receiver Groups now available from Colt! These 20” Upper Receiver Groups feature the same barrel used on M16A2 and M16A4 rifles, which has a Government profile and feature a chrome lined bore and chamber, along with a 1-7 twist. Colt has paired two of these models with Magpul MOE handguards to make them fully modular. Additonally these are available with or without a charging handle and bolt carrier group.