I don't have the document, however like I said I know of it. Co-author of the book WW2 Armor Gunnery Lorrin R. Bird actually wrote about it some years ago, and the shells were said to weigh 20.61 pounds, making them of the PzGr type. This also explained the results as the early PzGr's of all calibers suffered from unreliable fuzes.
The later improved BdZ fuzed PzGr's reportedly worked extremely well, igniting more than 9 time out of 10, causing enemy tanks to explode or catch flames almost emmidiately after first penetration.