Saturday, November 13, 2010

So Here It Is - Project Complete!

Say hello to my first AR-15 from a pile of parts.
The upper is a 20" barrel DPMS in 5.65x45 NATO, not .223 (so it will shoot both).  The parts kit in the lower I built is also DPMS, so I guess this is basically a DPMS AR-15 - except for the actual lower receiver forging and the work I did. 

I decided that for the time being, I would just serialize it.  This is easy in CNC - too easy, in fact.  You can spend an hour picking a font and getting it the right size.  Not that I know anyone who did this.  There's a wonderful little free utility that will generate G-code for engraving easily, DeskEngrave.  Here's my serial number.
There's a geek joke buried there.  The serial number is in two's complement.

I bought a couple of special tools for it, and the Midway USA "Gunsmithing the AR-15" DVD.  Being a company that sells, "almost everything for gunsmithing", they have a ton of tools to help you.  Lots of custom-machined little pieces of plastic for various fixtures.  If you're going to build a lot of them, then by all means they're a labor saver.  But for one or two, it's easy enough to get by without them.  I bought a couple of roll pin starters, and one little tool for helping to put the take down pins into the housing.  Yeah, they would be trivial to make if you had the dimensions.  I would recommend the DVD or something similar.  Watch it before you start.  Then watch it again.  It's really pretty easy to put one of these things together.
I only made two little mistakes.  I tried to put the trigger in backwards, but caught myself.  Then I put the wrong detent pin and spring in the safety and couldn't get the spring in for the last take down pin.  Once I realized I had the wrong spring in the safety, I took it apart and rebuilt it properly.  Everything works fine dry.  Forecast for tomorrow is for another beautiful day.  I think it's time to see if it shoots! 


  1. Looks very nice! Am interested to hear how it shoots!

    Nice 2's complement S/N, too!



  2. Congratulations sir! That's some very nice work. I look forward to the range report at some point in the future.

    I don't want to give away the puchline if I'm getting the joke, but to see if I've got it let me ask - could we sign extend your serial number to 8 bits as 11110001 ? It's gotta be fun to be able to make your own serial number. How about 42415446207375636B73 - ASCII hex for "BATF sucks". Of course all the geek jokes are surely wasted on the intended subjects. Still fun for us though.

  3. Leveraction - the joke I was thinking of in 8 bits would simply be 10000001. I like yours, but like you say, it's a bit long.

    I couldn't bring myself to make it the square root of -1. That would be too unusual. The number I'm using could be a company that formats their serial numbers with year then sequential number, so 10 001.

  4. Got it... You know, there are 10 kinds of people in the world, those that understand binary and those that don't. =) pi would be a cool serial number as well, or maybe exp(-jwt) or ln(0) - the possibilities boggle the mind!