wow the more i dig the more info i have to sort through. options are every where like chrome lined or stainless barrel. chromed or stainless bolt and carier. i think i want to get the barrel with the gas tube and block so i dont have to worry tuning the ga system. voltor has a upper that might work well the more i read it seems the one in eight twist is what i want it looks like i will be spending about twelve to fifteen hundred buck to make the rifle i want... then optics this is going to get pricy.