Machining an AR15 lower receiver

[Highpower]

And this is the set-up. Because of a small amount of backlash in the quill splines, I needed to be able to keep the cutting tip from wandering back and forth as I worked the tool up and down with the quill feed handle. So after locking the spindle on the mill I wrapped the BRRB (Big Red Rubber Band) around the socket head cap screw and stretched it to the back of the mill. That kept the spindle splines pulled to one side effectively removing the backlash, while still allowing the quill to move up and down to let the tool cut.


This is where my little spot circles on top of the deck come into play. The apex of the arc is where my squared corners need to be.


With the magazine well finished it was time to repeat the process on the rear half of the forging to hog out most of the metal for the fire control pocket. That is where the trigger, hammer, springs & pins, etc., (the inner workings) are housed. However this pocket does not go all the way through the receiver like the mag well, except for the opening for the trigger.


There is also a hole that must be drilled into the receiver extension threads at an angle, that houses a buffer retainer and pin.


There are several other steps that I didn’t get pics of, but they are equally important in making the receiver functional. Drilling a couple more small holes for springs and detents. Milling slots and drilling pin holes for attaching the trigger guard plate. Drilling and tapping the hole to attach the pistol grip. And chamfering the bottom edges of the magazine well to make it easier to guide the mags into the well.


Final views coming up….