[NVDave]

Those are M-3 “Grease Gun” submachine guns. Fired a .45ACP cartridge. They had barrels that would allow them to fire 9x19 rounds in some cases.

They were produced to bring down the cost of sub-guns, because the Thompson “tommy gun” was (and still is) a very expensive, exquisitely machined piece of work. Those are mostly sheet metal stampings.

[Gandalf_The_Gray]

They had barrels that would allow them to fire 9x19 rounds in some cases.

Barrels were steel tubing w/o rifling, just a plane old smooth bore firing a big chunk of lead.

Regards,
GtG

PS War time production brought the straight blow back (no Blish lock mechanism) Thompson down to about $78/each, the M3 was $11/each.

G