http://www.saami.org/PubResources/CC...20%20Swift.pdf
They just like saying head space.
There is no case head protrusion on the 220 Swift chamber, the 220 Swift with a rim and the belted mag case present a complication that has been with us forever, keeping up with two thoughts at the same time.
My opinion, the ring should not be there, I will assume the Model 70 is an older rifle as in pre-64.
F. Guffey