This set is so light that my wife picked it up and asked why I ordered a plastic gun. All the milspec pieces I have installed have fit perfectly. It is super light and beautiful, slightly off-black, not an absolute Black which makes it stand out. The Magpul MBUS sights sit perfectly in the pic rail and the Geissele trigger fits great (you just can't install with the slave pins installed so it makes the install a little difficult). Overall this is a fantastic receiver set!