Need ID on 30mm projectile dated 1972

[cannonmn]

Here are two photos of this 5.5-inch-long projectile with copper rotating band from manufacturer code "MM."

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I've been getting what I could from my junbled copy of Dale Davis' report. What photos I could view in it are very poor quality. So I need help.

1. Based on some of Davis' comments, I'm guessing this was used with the GE gun in the early 1970's competition for the 30mm US aircraft gun, but was it?.

2. What cartridge case was used with this particular projectile, as far as case length and case material?

3. What manufacturer is indicated by the "MM" code?

Thanks and Merry Xmas!
Cannonmn