I started with a .357 Mag barrel from a Timberwolf rifle. The outside was ugly, but the inside was perfect.
![Image](https://photos.smugmug.com/photos/i-nBjLMG3/0/e916d437/M/i-nBjLMG3-M.jpg)
I bought a Turkish folding 12ga Shotgun for $89.
![Image](https://photos.smugmug.com/photos/i-N3zg2qM/0/7dafebb8/L/i-N3zg2qM-L.jpg)
Faced off the loading ramp, turned a recess for the rim, and cut the extractor notch a little deeper:
![Image](https://photos.smugmug.com/photos/i-6RgXMjg/0/8a8a377f/M/i-6RgXMjg-M.jpg)
Turned the barrel down to fit into the shotgun barrel:
![Image](https://photos.smugmug.com/photos/i-qz97R5c/1/ebcdbc88/M/i-qz97R5c-M.jpg)
Removed the vent rib and threaded the barrel for a scope mount:
![Image](https://photos.smugmug.com/photos/i-KZckjgj/0/8bb17630/M/i-KZckjgj-M.jpg)
Installed the mount and milled some more slots.
![Image](https://photos.smugmug.com/photos/i-rtQBMjn/0/bad003ca/M/i-rtQBMjn-M.jpg)