At the moment, it's stalled waiting on the reamer and tap. I should be getting pretty close. 4d rental told me it would be around the end of this month before they can ship it.
I've threaded 12 ga barrels before, but never had to get this into it.
I have a lathe and will be using a taper reamer to open up the rear of the 20 ga choke so it doesn't snag the wad. Essentially, opening the mouth to the diameter of the 16 bore. There's not a lot of extra meat around the external of the choke tube, but it just has to be enough.
Since I have an open cylinder bore barrel at the moment, that's how I am measuring the bore.
I only plan to use this one choke, so I'm not going to engrave it with anything since it will stay in the gun. And I also don't have any threaded 20 ga barrels either, so won't be a problem.
The biggest concern is taper reaming the mouth of the choke itself. I'm not concerned about boring and threading the barrel. There's a lot of meat around the barrel wall.
