Two of the guns pictured are from the 1919 series.....(the one that looks like a '21 sans stock, and the one with the aluminum grips ) One was a 1919 prototyple designed to be manufactured with a bare minimum of internal parts.....
The "annihilator " guns....with shrouded bbls, may have been late 1918 production, but aside from a small mention in "American Thunder", I've never seen or heard anywhere else that any were on their way "over there"
Bill Douglas in Dunedin,FL has a pretty large collection of prototype guns......including many 1919 variants......you shoul find his TSMG video.....it's quite good
I'd ask over at machinegunboards Thompson board......you'll get a definitive answer....