So, I've stashed the Dolep pipes somewhere and can't find them at the moment, but have some others to show.
The first one shown above is from the Shaw gun. It's interesting that it was rolled from sheet that wasn't of sufficient thickness to for the tab, so they just cut a mortice to accept another piece of material and brazed it in place. If you look carefully you can see the joint. The other slot seen is just to clear the underlug that happens to intersect the pipe mortice in the wood. Note that the bulbous bands are filed off squarely where the pipe is inlet.
The second example is a wax pulled from the Cookson gun. It can't be seen clearly, but I do recall the bands were so high that really thick material was required. With this the case the tab was just filed from the material. I think the original tube was just a brazed butt joint. Note that in this case the bands aren't filed off in a square fasion but beveled off in the area to be inlet.
The final pipe is from a very nice Italian carbine. I think it's shown on my website. It's pretty similar to the Shaw. Interestingly enough it doesn't show much flair to the bands. They were obviously hand filed, but I don't think there was an attempt to make a flare. Turning would work great for something like this.
I need to look more for the Dolep pipes.
Jim