Wednesday, February 27, 2013

You Can't Stop The Signal 3: Defense Distributed Mk.III Receiver

Rapid-Prototyped weaponry continues to advance at a fevered rate.  Here are my previous rants on the subject...

You Can't Stop The Signal, Part 1

You Can't Stop The Signal, Part 2

So, in the meantime, a new movement called Defense Distributed has arisen, from a group of Texans down in the Austin area.

DD's mission (their website is here, their Facebook page is here) is to make AR-15s and other weapons as open-source as possible.  It's a two-fold goal, in my view:  to democratize the means of self-defense, and to push the envelope in alternate manufacturing methods.

However you feel about weapons and people's rights to defend themselves (a basic human right by any means necessary, in my view), the boys at Defense Distributed definitely know how to push people's buttons.

They've released the third version of their lower AR receiver, heavily modified from the standard pattern to compensate for the different materials used in rapid prototyping.

Here's a youtube clip of them doing a successful firing test, putting out over 600 rounds.  Their previous iterations didn't make it nearly this far.  The vid's a bit over the top, but so what.  Who doesn't love the sound of hundreds of rounds, accompanied by classical music? ;)

If you go to their website at, you'll see the browse tab.  Click on that to get downloads of this or many other different receiver files.

This particular Mk.III file downloads in .step format, but imports to Rhino nicely.

As a matter of fact, I've already had my way with it.  The DD folks had to make the rear takedown pin smaller, no doubt to retain structural integrity (this area is where most plastic ARs fail).  I made it standard size, but swapped out the use of the standard takedown pin with a stock industrial quick release pin from McMaster Carr.

 Here you can see the modified file in the foreground (with digital pin), the stock Mk.III receiver in the middle, and the ubiquitous download in the background.


Just so as not to appear rude, I also made an offset sleeve adapter for the stock Mk.III receiver.  This would push into the rear hole of an AR's upper receiver, and when aligned, would allow a .125 diameter rod or pin to hold the rifle together.

Pretty cool, eh?  The real world is becoming "hackable."  3d printer in peoples' homes, digital sculpting capability in every desktop computer, and cncs in every garage are going to make amazing things happen.

Stand by for the next industrial revolution!

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