Here is my entry into the AR Build-off, “Ugliest Rifle” category. It would have been a lot prettier, but I don’t have Fluffy to give me aesthetic advice!
It is a receiver made from .100 4130 sheet formed to shape using homemade dies. It was based loosely on the Bill Holmes version of the AR lower, but I departed from his path pretty quickly.
I used the .100 metal for a few reasons. First, it’s pretty tough and herky. Second, it made sense dimensionally. If I called a magazine .900 wide, I bent the mag well to that, and then bent the “U” that makes up the FCG holder portion to .900 OD, it made the ID .700. Worked pretty well, I think.
The bear of the whole thing was the buffer tube tower. I was trying to make this along the lines of my OhmsResearch AK, in that you didn’t need a lot of fancy tools to make it. Well, I ended up cheating and using a mill on this proof-of-concept lower, but I am chock full of ideas on how to make it easier on the next one! Anyway: Buffer tower. I found some tubing with an ID (1.180) that just barely allowed the threads of the buffer tube to slip inside. I ended up using a combination of JB weld (Thanks to a guy who posted a thread somewhere called “Mujahadeen AR-15) and setscrews to secure the buffer tube to the tower. It is not removable, though of course the buffer and spring are. Without a large (1.5” ?) end mill, I had to pretty much trial and error the curvature of the tower. For me, it was harder than it looked! I managed to get a template made, so I could so it without too much fuss.
Of course, I did not drill it for the detents for the front or rear take-down pin, nor the selector. Instead, I drilled and tapped the ends of these and secured the takedown pins with 8-32 screws and the selector with a 10-32 and a washer. I drilled the underside of the selector, and put a small spring and detent ball in there to make the positive “click.” I also used low temp (575 degrees F) silver solder to attach stops.