I have been gathering up parts and pieces to build a 300 blackout for this armors class I am about to take. It is a budget build. I want the knowledge and don’t really care about the quality of the rifle per se. It is basically just a bunch of Mil-Spec components. The AR platform is very straightforward but I want to understand more of the whys behind design. Many of my customers talk about building their own AR but essentially all they do is purchase a lower and upper already assembled and pin them together. In my mind that is not building your own, until the tiny spring and detent from the mag release button launches out of fixture on you it is not the same!