Ok, I finally had the time to get to your requested measurements. Very sorry for the delay. First, i’d like to mention that you have a early mod M865 and not the E2 variant as yours has the pierced cone verse the E2 slotted cone. Both designed to use the LKL principle to reduce there range. Anyhow, I photographed my M865 pierced cone variant so I could print it out to use as a diagram which I latter scanned back into my computer. I am not good with computers and am very sorry if the pictures are to big. I have not figured out how to shrink the file sizes. If a moderator wants to do it or tell me how, please feel free.
I hate reading calipers so I labeled each measurement to correspond to a numbered photo showing the calipers. Please note, that this particular M865 case I used to measure is made from a museum replica constructed of fiberglass that was molded from a real CCC. The projectile and aft cap are inert and real.
This photo is from a factory cutaway of a M865E2 round. I am using it to show how the CCC case connects under the black rubber gasket on the projectile. Measurement # 9 does not include the additional case height required to do this.
I wish you the best! Send pictures!