Unless the Thompson’s are sitting in a forgotten warehouse, I’m guessing that those from WWII were scrapped decades ago. Note that none were used in Korea or Vietnam. The old grease gun was kept because it was easy to store inside a tank as a ‘crew weapon’ for the crew to have something other than their pistols when dismounted. I think that the grease guns are now gone from the Army’s inventory, except for those in Army museums.
.45 ACP for close in fighting has to be preferable over 9mm parabellum.
Choose your platform but don’t tell me 9mm would be better or equal.
I am not an m16/5 fan but can see it’s benefits in 5.56 as far as carrying extra ammo over, say, 7.52x51…308. (Though I’ll take the latter when shooting into structures or cars).
If the little girls they allow in combat these days can’t handle .45 ACP, at least give them .40 S&W.