Keith mentions your gun at least twice in his book, Sixguns. On page 48 he mentions the DCM/NRA connection and W.R. Strong. Here he relates the story as Captain Strong using "several" clips, rather than "seven" clips, at Chateau Thierry. He mentions adding the checkered, arched MSH in the 1920s, along with the shorter trigger and longer grip safety. He also added a wider rear sight and Patridge type front sight.
On page 116 he mentions having "the King Gun Sight Company, now known as the Ricky Gun Sight Company, of San Francisco, fit higher front and rear sights to my old .45 Auto, and it then became much better for long range shooting...."
When D.W. King died in 1945, many of his parts and ideas were stolen by gunsmiths who worked for him. King made his own parts. Some of his former employees started Micro and copied his sights but they did so by infringing his patents. Another group of employees negotiated with his widow for patent rights and they named the company "Ricky" after one of the founder's young sons. So, Elmer's gun would have had the sights changed twice; once in the 1920s and again in the late 1940s.
AFAIK, I have the most complete list of N.R.A. marked M1911 pistols, compiled over many years. Your gun falls in the right range but does not appear on the list. I don't know of any that were sold through the NRA without the stamp but I guess it's possible.
Regards,
Kevin Williams