Don't own a colt M4, but I did build an M4 with a Spike's lower and PSA carbine upper and used the Magpul MOE stock, Handguards, pistol grip, and flip up rear sight. I am happy with the Magpul stuff, it is light weight and durable as long as you buy the USA made Magpul products and not the ones made in China that are made cheaper for primarly airsoft guns and sold on ebay. I would recommend building a M4 rather than buying a Colt for the price difference.