
I found five different types.
Type A is standard front stamp and no manufactures marks what so ever thus maker unknown.
Type B is standard front stamp and has USCO stamped inside rear strip
Type C is standard front stamp but is reversed and has USCO inside rear strip
Type D is a different format front stamp and has U stamped on the back of the strip.
Type E is standard front stamp with MSCO stamped on inside of the strip.
Five different styles, and I thought I only had one!
Regards
Murray