Your eyes are better than my aged orbs, I didn’t notice the full bead on the WW I cup. Most astute.
If you really want some info on US mess gear, this link will take you to a site to download a pdf of great pics and info:
http://www.history.army.mil/html/museums/messkits/messkit.html
BTW, one of my very first canteens has a metal cap, but its a 1944 canteen.
Placed in the 1918 cup and it looks like a WW1 set in pic.
And no, my eyes aren’t that sharp, just knowledge about canteens.
Good thing bout stainless canteen is u can put it right in Fire ta boil water