I was saying the upper is harder to build (but still easy) compared to a LOWER, unless said lower is an 80. So, lowers like his Aero (I used them on my first 3) will be easy to finish into a working gun.It's super easy - insert barrel, torque the collar, install gas block and tube, throw on the muzzle device and rail... dust cover and forward assist if you don't use a slickside.
What does an 80% have to do with any of it?