I’ve started a 450 Bushmaster build. Parts list so fat is: XXTreme Barrel Company 18” mid gas 1-24 barrel, Toolcraft BCG, KAW Valley linear comp, Acme Machine 12” keymod tube, low profile gas block and tube, and Burris Fullfield II 3-9x40 scope with PEPR mount. Aero XL upper should be here by the weekend. I’m going to use an Aero gen II lower with EFX rifle stock I already have. This will be my first venture into the big bore AR world, and I’m excited! I bought 2 boxes of Hornady 250 grain FTX to get me started, but I’m collecting the components to reload this thumper.