Machining an AR15 lower receiver

[Highpower]

Ok, back to work….
Here I am laying out the position of several corner points that are located around where the magazine well will be. I just barely touched the surface of the deck to give myself a visual indication of where each corner should be so that I don’t make a mistake and accidently cut past where I’m supposed to stop cutting. There is a small radius to be cut into the front of the magazine well to provide clearance for a seam on the magazines themselves. Drilling a hole down through the forging at the front of the deck leaves a perfect radius after the bulk of the metal is removed.


A series of ½” holes is drilled through to remove the majority of the metal from the mag well.


Then plunge cutting with a larger end mill roughs out the center of the mag well.


Due to the cutting forces of the mill and the fact that I was using WD-40 as a coolant/lubricant, I started to have problems with the forging starting to tip and slide down the side of angle block that it was clamped to.
At this point you can’t put too much pressure on the holding clamps because of the now, thin walls on the sides of the mag well. I could not put any kind of support underneath the well because I had to mill completely through, top to bottom. So I dug up a scrap chunk of aluminum and drilled a hole through it. Then set it between the front pivot pin lugs and stuck a screwdriver through them to hold it in place.
Setting a machinist jack out in front of the mag well bearing on my makeshift support gave me the clearance I needed for the cutter, and kept the work from moving out of position again.


A smaller endmill was used to make the final finishing cuts on the inside walls, and bringing it closer to its final shape for holding a magazine.


Unfortunately I do not own a shaper so I had to make one for squaring out the corners inside the mag well opening. It’s just a piece of round stock with a carbide insert screwed into the end of it.