7.62x51 cartridges - clear plastic case body

Can anyone identify the origin of these NATO cartridges?

The first two are blanks and clearly from the same source. Neither has a headstamp. The case bodies are clear hard plastic sealed at the tip with a reddish brown plug. The case head and interior are aluminum. The primers are flat brass. Powder is clearly visible in the top cartridge. In the lower one, the powder is held in place by a brown foam plug. There is no evidence that this was ever present in the top cartridge.

The third blank cartridge also has a clear hard plastic case, but the tip is open. The case head is made of opaque gray plastic with no headstamp. The primer is flat brass. The powder is retained by a foam plug. There is black lettering on the case side. The start is worn and unreadable. It then reads 0 60.

The last is a ball round. The bullet is GM. The case is one piece hard almost clear plastic. There is no headstamp. The primer is flat brass.

Dave S

There are more variations of low velocity rounds, I have a white plastic, blue plastic, all plastic including bullet and there is powder in the cart. Vic