I don’t know how I missed this one but those paintings are absolutely fantastic!!!!

Correct, but the CIB was not made retroactive to WW1 as far as I know. Honorary seems appropriate for his WW2 service.

. The Longest Yarn Knitted panels.   The longest yarn 80 knitted D-DAY panels are on display in a disused church at Saint Hilaire Petitville,  Carentan.  The roof of this church can be seen in the fourth photograph June 1944 just left of centre above the truck with the white star.  The church is hidden behind a tall Green tree in the fifth photo taken in 2022.  The bridge in the 1944 photograph is where a 94 year old veteran Sam Boyack fought with the 83rd Division, and I had the pleasure of taking him to this bridge on his first visit to Normandy after fighting here seventy years previously.               Norman D. Landing, Forum Normandy Correspondent, 07 April  2O26.   ..  

To my knowledge distinguished service crosses are named and named Navy Crosses are considered extremely rare because it is not common but I could be wrong.

When did they name Navy Crosses?

Your grandfather had quite the collection!

The trigger group is milled and not stamped so it’s clear it’s not original to the rifle. I’m thinking that it was made by Winchester. IBM M 1 Carbines had a stamped trigger group. It’s not surprising to find that in an arsenal rebuild. They don’t call them mix masters for nothing.  

> I'd readily say he deserved his CIB, honorary or otherwise - and thought so in 2010 as well.

From what I was able to find it looks like he was with the the 15th cav and not the 113th.   https://aad.archives.gov/aad/record-detail.jsp?dt=893&mtch=1&cat=WR26&tf=F&q=39085805&bc=sl&rpp=10&pg=1&rid=7605238    

General MacArthur saw a lot of ground combat during WW1.   7 Silver Stars, 2 Purple Hearts..    https://www.militarymedals.com/warhero/general-douglas-macarthur/