At SLICS I got an experimental US made case in 23 x 133 Calibre. The fininsh is a very light matt green plating. The markings are (printed on side of case in black ink):
Apparently these are very rare to find as loaded rounds, but the unfired cases are fairly common. Can anyone tell me any more about what this case was intended to be used for? Was it an aircraft gun, anti aircraft, helicopter, AFV etc?
Thanks in advance for any info.