I just came across this DTIC report which as usual is very detailed and sheds a lot of light onto the subject as well as on technical issues and requirements.
Thought somebody may appreciate it as much as I did.
DEVELOPMENT, MANUFACTURE, AND METALLURGICAL STUDY OF THE PROJECTILE, PRACTICE, 30MM, T304. PROJECTILE, PRACTICE, 30MM, T241. PROJECTILE, TARGET PRACTICE, 30MM, T328. SHELL, H.E.I., 30MM, T306E10