I’m not really into 80% frame builds but I was given an 80% Sig 229 frame and thought it may make for an interesting project. I watch some YouTube videos and people were using jigs and tools from Matrix Precision. When I went to their website and saw the prices I decided this was not the route for me.  If one were to buy a frame and all the tools necessary form them the price is $633, not including all the parts. That’s a lot of money to stay off a “list” that I’m already on.

Luckily for me I have access to a milling machine and just enough knowledge to hurt myself. The first question was how to secure the frame for milling. I keep trying to think up different ways then I notice something. The top of the pistol and the mag well looked square and parallel to each other. It turns out my suspicion was correct so I should be able to clamp it in the vice over parallels. The flat area on the grip handle should be enough to set it on the parallels if I cross over the bottom grip screw hole. I thought I may have to figure out some way to support the dust cover because it wasn’t on the same level as the grip flats but once I clamped it in the vice it was more than secure enough.

I made sure the front portion of the dust cover was sticking out of the vice jaws so I could use an edge finder on the top of the frame. The guide sheet form Matrix recommends a rail cut of .120 to .124 inches wide starting .114 to .116 from the top. It doesn’t give a depth. I had an 1/8 (.125) end mill already so I decide it was close enough. Some of you may notice I used a drill chuck to hold the end mill. I know its not the correct way but its all I had and it seemed to work fine. In fact my West German P229 rail cut is larger than that. I also measured the depth of the cuts to give me some idea on how deep to go. They state in the guide that the dimensions are approximate and they are right. Using the 1/8 cut the rail just wide enough to allow the slide to fit. If I had of went any smaller it wouldn’t have worked. I ended up going .13 inches deep and the slide is extremely tight with no play at all. In fact it may be too tight.

After cutting the rails I then used the edge finder on the front and top of the frame and used the recommended measurements for the trigger and disassembly latch holes. The recommended hole size for the disassembly latch was .354. I started with a center drill bit and then moved up in size until ending with a 9mm drill bit. The latch dropped in perfectly. The recommended size for the trigger hole was .177 inches. I started with a center drill on this one also but went straight to the .177 bit afterword. I ended up going to a .182 bit before the trigger pin would fit. Lastly came the hammer strut pin hole. I set the frame on the mag well in the vice. I started with an end mill, because of the curve inside, so the drill bit wouldn’t walk. The recommended hole size was .390 inches but I stopped short of that and finished with the end mill for the hammer strut clearance. I could have probably have done the whole thing with the end mill in the first place.
It assembled pretty well although a little tight. The ergo grip doesn’t fit right and the slide stop isn’t working correctly. I haven’t had a chance to shoot it yet but hope to in the next day or so. Once I’m happy its working I will more than likely Cerakote it.

Videos at the bottom for the ones that like to watch amateur machining.  







https://www.youtube.com/watch?v=xNu1XUgYmp0&t=1s

https://www.youtube.com/watch?v=ODUDfy6bx48&t=1s

https://www.youtube.com/watch?v=32VbWn1dSnk&t=1s

Buddy i have seen P229 scorpion elite's NIB for $668 with N/S, G10 grips, & SRT in the last week on line. But if it keeps you out of trouble, or away from the whiskey bootle, build it.