I ordered an upper/lower forging combo and then another single upper because the uppers don't seem quite as difficult to finish as the lower receiver. The casting is pretty much dead on...The 'A' marking and the line marking around the bolt cam area are cleanly cast and visible, so although it would be easier than a manual mill, you don't necessarily need a CNC machine to finish one of these. I'm figuring complete finishing will require some special bits like a slot cutting bit (for the charging handle slot), thread milling bits (for the barrel nut thread - manual machine users will have to find other ways to cut the threads), and perhaps dovetail cutter (for the picatinny rail - but other methods could be used to cut the angles). This is a neat novelty item or good for a side project, but I definitely wouldn't buy these thinking you can save money by doing it yourself. Remember there's a very good reason a finished upper cost much more than one of these forgings!