Finally.....I purchased the lower from a friend over a year ago. It sat in my safe.He was going with a tactical 6.8mm setup. He already had an OD pistol grip and collapsable stock, and the goofy CA legal bullet button thingy. I wanted a flatrail hunting setup in .223.I finally purchased the complete upper (Bushmaster Predator, 20" barrel with 1:8 twist) and a Nikon Buckmaster scope (BDC 14.5 - 14 x 40) and installed it with generic scope mounts.I found a collapsable stock and a scope don't mix, so installed an extended charging handle, changed the stock to a Magpull adjustable in black (didn't care for the the OD green) and changed the scope rings out for a Burris one piece (PEPR). While I was at it, I added a black Hogue pistol grip. (Whoda thunk there was a spring and pin in there somewhere? Had to search the carpet for those.
)I finished it off with a Harris Bi-Pod.Now it's perfect. I have about 400 rounds through it without any issues, and I love it. Right now the barrel is more accurate than me, so I need more practice. I put the last 40 rounds through fist sized group at 100 yrds.