Thank you so much for your work Mike.
But something seems strange to me : you say the difference between the diameter of the body and the diameter of the groove is .008, which means the ring is .004 or .003 thick at the end of the process, which seems very little to me, and what I can see on the last picture seems more .04 than .004 . Maybe inches are messing up my metric mind, but are you sure of the groove depth?
Did you ever try with other metals?