I love picture number 2 showing the M2 .50 Cal HB Machine gun and in the background you can see where the mount is for the deck gun that had just been removed, they didn't take the time to plate over the mount or remove the barrel lock that was laying flat on the deck.. Funny thing about the M2 is that the reciever housing, slides and barrel haven't changed in almost a hundred years.. Recently the Military had the barrel and slides replaced with an easier removal barrel which is like the M249 SAW and the M60 MG (which was roughly based on the German WWII MG 42) The back plate was interchangeable from having the double handle with the butterfly in the center with the locking ring to make it fully automatic, to the single handle back plate.
Worked on the M2 in Korea, USofA and Kuwait/Iraq, was the Battalion Armorer for 1-3 Avn Atk during OIF1 and by that time had been working on them and teaching them on and off for roughly 5 years
Darrin