This is my first real custom work involving metal working. I always liked the Mac-11 from RE2, even though its been years since that game came out. It was the first thing i thought of making when I got my KWA Mac-11, and no one actually seemed to manufacture the right part. There were some close, but none were quite right. Unfortunately I lacked access to a MIG welder so i could never actually do it myself.
Well, I now have free use of one, so this project finally got to see the light of day. I started off with a barrel shroud from a Browning M1919a4, cut down to 10 inches. The inner barrel is a section of 1/2" steel pipe, and the end caps are 2" OD steel washers that were ground down to 1 7/8 OD. On the inside the inner pipe is welded to a 5/8-11 nut in order to thread onto the Mac-11. After it was all welded, I ground off the excess welds, polished it up with steel wool, and gun blued it.
The inner pipe is wide enough in diameter that the shots never contact the barrel wall, and it should act as a nice covering for an extended inner barrel.
So heres what It looks like:



I still need to run a bore brush through the inner pipe to clean it out a bit, But I dont have one quite large enough at the moment.
Now it has this great metallic ring when the gun cycles too. So, maybe its not quite as impressive as some of the other work on here, but its a start!
Edit: Also as a side note, The Mac-11 also has a G&P steel body kit on it, I mention this because the weight of the ported barrel would likely be enough to crack the original plastic body. With the steel kit installed, everything works fine though. For plastic bodied mac-11's this would probably have to be made of PVC or Aluminum.