Resurrecting the thread with another one I just finished up. This belongs to a forum member who has been waiting on it for several months now, but he has been kind enough not to bug me about it.
It started out as an artillery barrel that had been cut and fitted with some kind of muzzle device. I did this one the same way as the first one, but this time I also made a jig that makes it easier to get everything plumb and level in the mill.
And Sheepherder: I owe you one, your barrel thread has been the inspiration for this.