Ok So I am wanting to try building an upper. I just want one that will chew up blasting fodder doesn't have to look great. Now to the questions. 1. On the 16" barrel I thought 18" was the shortest barrel you could have? Cause I don't want one of them stupid looking bloop tubes on the front maybe just a std M-16a2 type. 2. For a range fodder gun would you go with 16 or 18"? 3. what tools am I going to need to purchas?