Extra credit for Bro. Larry. That picture is not of Eisenhower's M21
https://www.youtube.com/watch?v=J6EJkvSJxbQ

President Eisenhower shooting clay targets launched from a Naval escort vessel while cruising the Potomac aboard 'Barbara Anne' with Capt. E.P. Aurand, Sept. 1960.



Eisenhower and George C. Marshall both owned Ithaca doubles, but I don't know the grades nor locations thereof. Marshall's Ithaca is not listed in the Marshall Museum
https://www.marshallfoundation.org/museum/
I can't find information as to the O/U in that image - it certainly could have been a plantation loaner

Interesting infro re: Presidential guns here
https://www.americanrifleman.org/articles/2016/2/15/the-guns-of-us-presidents/
Roosevelt's Frederick Adolph .450-500 NE "Big Stick" never made it to Africa

More infro re Hemingway's M21 and Harrison's Optimus
https://www.fieldandstream.com/photos/gallery/2016/09/the-top-12-most-famous-shotguns#page-7

https://sites.google.com/a/damascusknowledge.com/www/home