Here's a photo of [id=236180627;this piece] from below, showing the huge bubble which removes the lower part of the threads, and runs around a good portion of the interior. The threads in the piece would normally have run an extra 1/2" to 3/4" into where the bubble is formed. The photo doesn't show it too well, but coupled with the misaligned dome... man is this piece unique!

All the best!