I went back to Ancestry.com again. William L DeCamp, 1901-1993, Cincinnati, Ohio. That fits the letters, but Mr. DeCamp worked as an assemblyman in an automobile factory. In the 1940 Census, he had a wife & 3 kids. All that would suggest that this Mr. DeCamp is not the man who commissioned a high-end G&H rifle.

There is more than one L.W. DeCamp. Sometimes people reverse their given names.