Follow-up on my earlier post. I got the letter for my .44 HE. It is factory nickeled, and is a year older than I thought, shipped as a one gun order on September 12, 1923, so it turns 99 in two months. The frame inside the yoke has the Springfield Armory "S2" mark and eagle stamp, so it is a leftover .45 HE frame proofed for WWI, and the cylinder was heat treated, as the treating started with #16600 (mine is #20943). No mention was made of the lanyard ring, so even though it has the hole, it likely never had the ring, and the hole was never plugged. It was shipped with gold medallion checkered square butt grips, which I have, they are not numbered, but now I think they are still original.
The letter is very much worth it. Thank you, Don Mundell!