A solid drill press and drill bits is all that is needed to ‘finish’ a 90 lower.
You may have hit the wrong digit key. The unfinished receivers cannot be more than 80% completed in the situation we are discussing. It is still not an easy job for most people. Most people need a jig to get things right. A milling machine is actually the more appropriate tool but I have a 6” cross slide vice that I have been meaning to do a little work on to get ready to make one of these.
Interestingly enough I did find a supplier selling an 80% completed polymer receiver tonight, which I was not aware of previously. The link I provided previously was to a company which sells an inexpensive CNC milling machine which will do most of the work automatically after you bolt your receiver into it. They are suppose to be
Yep...and FYI, if anyone has become interested in one of these projects due to this post....
DO NOT attempt to do the machining with a hand drill.
You need a good drill press and a good vice.
Buddy of mine here in CA screwed up a polymer and aluminum AR lower because he thought he could manage it with a hand drill and WalMart bits.