Replies

Here’s an example of an unfinished forging:

http://www.dsarms.com/prodinfo.asp?number=1001

Reasons to go this route: You can make any mods you want to the design, mag well, etc when you machine it out. You can buy a half dozen for the price of a finished lower. You can make a lower for each caliber you want, etc.

What do you need to finish this? Well, there’s two ways to go:

First, you could use nothing more complicated than a drill press and a set of files. The lower is forged out of aluminum, after all, so this isn’t like filing on 4140 cro-moly steel. It would go (relatively) quickly. If the urchins in Pakistan can carve a receiver out of a forging with a file, so can Americans.

Second route: A Bridgeport-style vertical mill. While this sounds expensive, it isn’t as expensive as many folks think. The collapse of the auto industry has flooded the market with used mills - you can pick up a mill for between $2K up to $4K. Once you have a mill and some tooling, there’s a whole field of stuff you can build for a shooting hobby - from scope rings and rails to front/rear sights, adjustable rests, etc. Matter of fact, there’s a whole host of things you can do that you couldn’t do previously in metalworking.

Vertical mills are incredibly versatile machines to have. Think of them like a drill press on steroids (and then some). Not so much because they’re so much more powerful than a drill press, but because they’re so much more rigid than a drill press. Their spindles are designed to take side loads, not just an up-and-down load on the tool. You put a cutter into the spindle, clamp the work to the table, and the table moves up/down/forward/back/side-to-side. On a mill, you feed the work into the spinning tool, and you can typically tilt the tool left/right, forward/back for complicated shapes.

Once you’ve used a mill, you’ll almost never go back to a drill press - even just for drilling simple holes.

EDM (electrical discharge machining) is the high-tech, high-precision (< .0001” accuracy possible) method of removing metal from deep solid pockets. Used EDM machines will set you back from $5K up to $10K, then they’ll need some consumables and tuning to get going, then you’ll have to learn some CNC programming to get them to do what you want. This is beyond most people, I’ll admit, but it is the way that AR-15 gunsmiths tend to hog out the mag well on a receiver if they’re doing a lot of them.