I have posted this to some FB pages as well as the BOCN and so far I have not got much back.
I got this projectile from the recent group of items I got. This one specifically came along with the 40x180mm Bushmaster dummy as they both came from a gentleman who worked at the factory. He only said that it was an unfinished 30mm projectile.
I noticed once I got it it is extremely similar to an M789 30x113b HEDP projectile except it seems to have a tracer unit on the back instead of the typical semi round bottom. It even goes as far as fitting a M759 fuze and the copper cone.
I dont know of any US M230 ammunition in use with a tracer unit, and I was unable to find any export rounds with one either. I was told on the BOCN that there is an experimental TP-T for the M230 but it is not in US service (XM977 TP-T). However the only photos of the XM977 I have found are not the same design as my projectile.
I am even more lost than when I began!