Ray Brandes has written an excellent treatise on machining an AR-15 lower receiver from an inexpensive “0%” forging. What follows is a photographic expo of following those instructions (mostly) to create a new AR-15 lower receiver.
For the most part, I will let the captions do the talking.
To start you’ll want an AR-15 raw forging, and the tooling plates described in the instructions. A lower parts kit is handy for checking part fits.
I just picked up a Marlin 917V, and after two shots I knew something had to be done about the trigger. On my first attempt to shoot I actually stopped pulling because I thought the safety was on! Regrettably, I didn’t check the weight of the original trigger, but it was 10 pounds if it was an ounce, and probably more.
New (to me) Marlin 917V
To build an AR-15 in .45, the bolt must be opened up to accept the larger case. This also requires some work on the extractor.
I need a chamber reamer to cut the chamber for the DI .45 carbine, so now’s a good time to demonstrate making one. The first step is to acquire chamber drawings. These can be found in a number of places. You may have access to SAAMI drawings, drawings from a reamer manufacturer, or drawings from quite a few different books for this particularly old and mature cartridge.
You will also need:
- Some method of indexing the cutter by sixths. (Fourths might be acceptable)
- A swiveling vise, or means of holding the work at an angle in the X-Y plane.
- Some O-1 (oil hardening) drill rod, of sufficient diameter for your intended caliber.
- A torch. Oxy Acetylene is great, MAPP is sufficient, and in a pinch a couple of propane torches would probably work.
- A magnet, on a stick or rod.
- Some oil. Used motor oil is fine.
- A drill press is desirable.
Having detailed the complete disassembly of a 1911, it’s only fair to show you how to put it back together. Much of the process can be considered “disassembly in reverse”, but there are some details that we need to pay attention to that were ignored in the teardown.
We’ll start with the slide.
Push the extractor back into position. Note that the hook should face into the pistol. The back of the extractor is such that it won’t go in correctly in the wrong orientation. Align the slot at the rear of the extractor, with the slot for the firing pin stop.
Slot in extractor which allows the firing pin stop to lock it into position
Extractor slot lined up with slot in slide
You can push the firing pin stop into position to help guarantee the alignment of the slide and ejector slots.