Star Shell Plate Identification

[Diesel]

I have several Star shellplates that appear to be .38 caliber. All of them are unmarked except for one that has a "U" stamped on the underside near the center hole. Does anyone know what that marking means?

Also, is there any reference to what calibers the shell plates will fit and how to identify them. The earlier ones are not marked.

Thanks.

[rbwillnj]

Currently I have half a dozen 38 Special shell plates, three that are marked with the U, and three that are not.  On the Star parts list, the U meant that the part was for a Universal machine rather than a Progressive, so it could be that the 38 Special shell plates marked with a U were intended for Universal machines, but I tend to doubt it.  I measured the shell plates that I have, and there isn't more that .002" difference in diameter between any of them.

I probably have over twenty shell plates, and only the 38 Special and 45 ACP shell plates are not marked to indicate the cartridge for which they were intended.

[Diesel]

Thanks for the info.