Shade Tree Armory Stage 2 Forging Project

Ever wanted to build your own AR-15 lower receiver? Didn't know that thousands have been built, it is completely legal, and that building your own lower can be more rewarding than shooting a factory lower? Read on!

The lower chosen for this project is available from Shade Tree Armory. Unlike so many partially completed lowers available to the enthusiast, this lower is forged, not cast. Forging is universally acknowledged as producing a superior lower than casting. The tensile strength, finish, and machinability of a forging exceeds that of a casting in every way. Yes, you can get a cheaper lower than those available from Shade Tree Armory, but in the end, after all of the work, why not have a better lower for a few dollars more?

I am not going to go into details regarding the legal issues. I will summarize them by saying the lower can be sold, given away, etc, freely, so long as it is not more than 80% completed. Before this level of finish, it is a chunk of metal... any more finish work, and it becomes a firearm, subject to any local, State, and Federal laws. It is up to you to determine the legality of finishing the lower. Basically, if you can legally own a post-ban AR type of weapon, you may build your own lower reciever.

Shade Tree Armory offers AR-15 lower forgings in three varieties - All have the critical mag well area EDM cut, with excellent tolerances and finish. The Stage 1 forging is the least completed. Stage 2 has the buffer tube threaded. Stage 3 has the fire-control areas milled, but skips the buffer tube threading so as to avoid breaking the 80% rule. I chose the stage 2 forging, as it was less expensive than the stage 3, and I wanted to do the fire control milling myself.

The following links will take you to specific portions of the project!

Machining operations and coordinates table

Part 1 - Initial Inspection
Part 2 - Preparing to Machine
Part 3 - Locating the Front Pivot Pin
Part 4 - Drilling the front pivot pin
Part 5 - Creating a locator button for the pivot hole
Part 6 - Planing the Top and End
Part 7 - Creating the 0.750" radius in the upper plane
Part 8 - Left Side: Bolt catch spring, hammer, trigger pin holes
Part 9 - Left Side: Takedown pin and selector lever holes
Part 10 - Left Side: Bolt catch and mag catch slots, selector stop bosses
Part 11 - Right Side: Pivot boss, mag catch slot
Part 12 - Right Side: Pivot pin spring vent, trigger guard
Part 13 - Right Side: Grip Flange
Part 14 - Left Side: Grip Flange
Part 15 - Flange Cleanup, Trigger Guard Slots
Part 16 - Grip, Takedown Pin Spring Holes
Part 17 - Bolt Catch Pivot, Selector Detent Holes
Part 18 - Top: Bolt Catch Slot
Part 19 - Top: Hammer and Trigger Pocket
Part 20 - Top: Rear Fire Control Pocket
Part 21 - Top: Deep Extension; Trigger Slot
Part 22 - Top: Buffer Stop Hole

Tips and Tricks:

Using an edge finder to locate the center of a round or bore