The 1919A6 is the only mass produced WW2 variant of the gun with a buttstock, made specifically because we didn’t have a super portable, sustained fire answer to the Mg34 and 42. Prior to this, we were mostly using 1919A4s, which needed a tripod or vehicle mount. I can’t find reference to it, but I can see the USMC using the A1 at the start of the war, since they were the forgotten middle child when it came to equipment until the last twenty years or so.
The Stinger is a different beast entirely, that’s the .30 AN/M2 Aircraft machine gun turned into a squad weapon in a machine shop on a ship, cludged together with aluminum parts and a garand buttstock. and I’d love to be able to gold order it, but I think it should wait for a pacific campaign.