I built this from all new parts. I am happy with it and I can't wait to shoot it. I had lots of issues choosing the parts I went with. I still would like to upgrade the trigger later. But the RRA 2 stage is fine....... I took it out today and fired it with 55gr Wolf ammo today. Worked like a champ! I used the following: Armalite M15 upper/ lower Wilson Combat barrel fluted 16 inch RRA LPK RRA National Match 2 stage trigger A.R.M.S. 41-B Silhouette Folding A frame front sight A.R.M.S. 50 M-CV rail system A.R.M.S #40L rear flip up EOtech 512 Standard charging handle POF flash hider Dan Young National Match bolt Chrome Magpul Mags/ Grip/ trigger guard/ CTR stock and pipe Standard buffer and spring Standard Gas tube Finish is Duracoat Snow gray, dusted with black and satin clear coat.