My information from a person involved in the project is that this was a US Army contract with Olin. These rounds come with a variety of sabots. A well known collector from St Louis who is no longer with us, .discovered quite a few of these rounds with different sabots mixed in a lot of fired cases from Olin. My understanding is that these were all experimental rounds. They were originally designed to shoot down the heavily armored Hind helicopters used by the Soviets in Afghanistan using a standard Soviet 12.7mm machine gun. Unfortunately that gun uses a muzzle brake and on the first test firing the sabots jammed in the muzzle brake and blew it off the end of the barrel. Quite a few variations of sabot were tested to find one that held together until it passed through the muzzle brake. This development was cancelled when a better solution was found. I have never heard of Charlie Wilson’s name mentioned in association with this round but then I never asked that question.
I think these rounds were discussed in an IAA article from the period.