Well, my flat spot kit is coming along nicely. I'll get pictures up when my phone and computer start getting along.
I went a bit unconventional with the stock. I turned down and welded some seamless stainless electrical conduit to the tower. I wanted a long LOP on this like a fixed A2 stock, rather than an adjustable carbine stock. No reason for it, just unique looks. With the tube being several inches longer than a carbine buffer tube, I plugged the steel tube with 1" rod, and welded my shoulder piece to that. It's held into place with four set screws. I'll have to evaluate how well this set up will hold up under fire.
Buffer spring and buffer slip into the electrical conduit as if they were made for each other.
As for the buffer retainer, I got creative. I had an odd piece in my junk bin, a 10-24 set screw with a spring loaded plunger. After drilling and tapping, and getting the depth adjustment right so the bolt had clearance, it works like a dream. And because the buffer tube is permanently affixed to the tower, I don't really need to worry about removing the buffer retainer in the future (although I can if need be).
I still need a magazine catch (my shop made catch didn't exactly work) and a fire control group. But everything cycles when its pinned together.
I'll be ordering another kit to build, and learn from my mistakes. I'll experiment with a 9mm conversion on my next one. Instead of using a block, I'll be installing a flat spot Uzi mag well kit when they come back into stock.
Also another build will give me the opportunity to attempt some weight reduction on the lower.
