Just built a couple of AR 15's From 80% lower receivers and assorted bits. Both identical with 18 inch stainless heavy profile free floated barrels chambered in .223 Wylde. Key mod hand guards and full stocks. Took me about 4 hours to mill out the receivers and 4 more to put it all together. Got another couple of billets ready to mill out but not sure what I am going to build them up to. Maybe one shorty and a 20 inch side charger, but the jury is still out on that. May even build one in 6.5 grendel.