Here is a high level overview of my fully custom built by yours truly AR15 300 Blackout. Heres some parts specs: Lover Receiver: S&W MP15 Trigger and lower parts kit: CMMG Buttstock: Magpul PRS Sniper" Barrel: AR Stoner 1:9 Twist SS Grip: UTG Sights: Aluminum UTG Quad Rail: UTG Duracoated flat Bolt & Carrier: DPMS Firing Pin: Titanium DPMS Buffer Tube & Spring: Advanced Technology MILSPEC