Checked several shells (mine, Dad's, and a friend's) 6 of the 31 shells were stainless (non-magnetic) 1 was carbon steel, plated and magnetic. The attachment rivets also do not look as nice.
3 of the 30 shells checked were carbon steel and plated and one was stainless. All with original nice nice-looking attachment rivets.
Wonder if there was a change in the material later in production.
Most of these 31's do not look like they have ever been worked on, but who knows ?
Could the change to stainless might have been to save $ by eliminating the plating process, just stamp, polish, and install. But the cost of materials was likely more. Who knows, mysteries of the A
