Do the flash holes in the cases look oversized?
A normal flash hole is around .080
Many different and special purpose blank, marker and tool loadings were made for many years on the 38S&W.
Most all of those used the Blank Load case which has an over size flash hole (approx 1/8" dia).
Military, industrial, theatrical and other uses.
There was a large supply of 38S&W empty unfired brass available some years back. It supposedly was MilSurp and was mfg'd to be loaded as a blank and used as a primer in some sort of launcher/morter(?).
True or not,,it was great brass! and copper as well.
The copper case was a common use for these specialty loads but they were also used in some earlier turn of the century loadings as well. Though these pictured are likely 60's vintage IMO.
Remington did set up an ammunition mfg plant in Mexico it seems at some point and then the entire opperation was Nationalized by Mexico or otherwise taken over by someone there other than Remington.
I was told it was there that the copper 38S&W cases were made in volume for these purposes and that some were also sold as new-primed cases with the Rem headstamp.
True or not,,I don't know. Supposedly the same opperation made the 41RF and 32Rf ammo that imported into the US in the 70's by Navy Arms.
Yes, they really made them of copper!