Hello, I am interested In building my own AR. I have never done this before but I build almost everything I own so it's appropriate . My question is in regards to buffer assembly. I would by the stripped lower, parts kit, and a fixed stock likely from Magpul. Where in this process do I get the buffer tube, buffer and spring? The parts kit doesn't contain it nor does the stripped lower, and from what I've read the Magpul stocks do not either. So, could someone provide guidance on this aspect of building an AR15? Thanks.