This is just Pissbacon's original idea, with a few modifications. And I'll warn you, it looks like shit when compared to the original. The breech action is essentially the same (with the coathanger idea), except reversed. Instead of the normal breech where a smaller piece of PVC/brass is inside a larger piece, I have a piece of 1/2" copper (it seems a bit bigger than half inch, even though that's what it says on the copper, the actual ID is 10/16") overtop of a nine inch barrel of 9/16" PETG (fits my darts kind of tight). The copper fit right over the PETG. Although I was sceptical of this at first thinking that the breech in the actual barrel would cause too much friction, I am getting 75' flat consistently with deadly accuracy using 1.5" stefans with size 3/0 lead splitshots for weights. And without further a due, the pictures (ignore the books underneath, they were just used to prop up the gun):

This is the top view of my BBB. Notice the fag stickers. Shut up, I like my fag stickers. And yes, I know the barrel is angled down, but when I shoot, it seems to jump up so the dart flies straight.

This a top view of the breech and clip. Here you can see the breech in the actual barrel. The clip is at an angle to prevent it from interfering with the movement of the copper cover. There is also a nice piece of a Coca-Cola box to prevent the darts from falling out.

This is just another angle of the breech and clip. What really adds to it is the piece of a Trident gum box used in the construction of the clip.

This is just a shot of the breech closed and all that hot glue that really made a mess of things, but hey, function over fashion.

Another picture of the closed breech, just from another angle.
That's all I have for now, and like I said, it looks like shit, but works pretty damn fine. I can't forget this: mad props to Pissbacon for such an original mod, it's what made me want to get a BBB.