This is a solid combination of parts that needs just a few cheap components to get it working 100%. Does not come with a magazine This build has a few very expensive parts and cool parts. Parts list as follows, Real steel CMMG keymod rail system unanodized Real steel trigger and sere CNC Ball bearing upgraded hammer Real steel trigger spring G&P selector G&P Bolt carrier and Nozzle G&P Barrel and chamber (inner and outer) G&P pistol grip G&P mag release G&P bolt catch/firing pin set S&T Polymer Upper and lower receiver S&T buffer/Spring/buffer tube S&T stock S&T aluminum charging handle Here's What this gun needs: New high strength hammer spring as the one that is installed is too weak and light strikes the mag, it is also missing the auto-sere and spring. I may find the auto-sere and spring but I don't know where it is. Both are super cheap parts. The other small issue is that the rail is mounted by clamp pressure only so it can be slightly offset if hit. Buyer pays pp fees and shipping. Willing to trade. This is an amazing deal for just these parts alone.