Started my first build last year. Going slow but it’s taking shape. Started with a Spike’s Tactical stripped lower. Added a set of KNS non-rotating pins and a JP Enterprises adjustable selector. Haven’t decided on the trigger group yet but it will be a drop in. Have a standard mil-spec trigger group installed for the time being. Will be using Magpul furniture except for the handguard witch will be the VLTOR CASV-EL along with the VLTOR modular upper receiver. The barrel will be a 16" Sabre Defence M4 Flat Top with 1:9 twist in 5.56. Plan other calibers later to include 6.5 Grendel, 30 AR Remington and 458 SOCOM. Should handle any thing I want to do with it.