....but I don't know if it ever fired these "cartridges" that the .45 1911 shoots. The tommy gun is marked "MGC Model Gun Corportion". ]
Open the bolt, remove the magazine and look into the 'chamber'.
If it is one of the blank firing models, it should have a pin in the center of approx 1/16" dia pointing back out of the chamber.
The bbl is solid from that pin forward. That allowed the 'gun' to be imported as a 'non-firearm"
Sometimes the pin is broken off but you can still see where it was attached in the forward end of the chamber.
Some had an allen screw under the chamber to allow removal or more likely replacement of the pin if needed.
The cartridge is slammed into the pin in the chamber by the closing bolt. The pin entered the hollow nose of the cartridge and hits an internal firing pin in the cartridge which in turn strikes a small pellet of explosive.
Upon ignition, the force of the explosion can only go forward back out through the hollow nose (the back end of the cartidge is a solid piece). The force is trapped by the plugged barrel, so it pushes the cartridge rearward opening the breech bolt and operating the action.
The cartridges are reloadable and the pellets were sold by the 'card' The bullet screwed into the case,,the small internal firing pin is loose to fall free from the cartridge when the 'bullet' is unscrewed.
The standard mag was a 20rd. US GI mags will not fit as issue, but can be modified to fit by altering the attachment slot and slimming the mag rail slightly.
A drum magazine came with the TSMG also. I believe it held 30rds. It had an internal set up nearly the same as the originals and seated into the gun as original from the side.
I have a drum body but no internals with it. Probably didn't work too well!
The TSMG model fires at a faster cycle rate of the real thing, but for theater, screen and plays, it was popular. It was a noise making SMG after all and a Thompson at that.
The recoil spring(s) are quite weak, this to enable the action to work with the blank ammo. But in the case of the TSMG, it does function as the real thing, firing from an open bolt,,and both Full and SemiAuto fire depending on selector position. It does have a Safe position too.
I think I have a pic or 2 of some of the cartridges, componets & packages they came in. If I can find them I'll attach them here.