There is no date to the file and the other summaries are not sorted in a comprehensible form. However, its from 1943 as indicated by the /43 suffix.
For whats worth, one may infer from the form that it responded to a question how ammo performed, as it stated to have had good experiences with Flak ammo. The emphasized
on the other hand tells me that the initial question was not related to Flak ammo but KwK ammo, which at that point was also distributed for the first time (8.8cm pzgr.39 appearing in quantity). Apparently, schw. Abt. 502 had not used KwK ammo until this memo was returned, explaining the from of the response. If that is assumed to be a believable hypothesis, it would point towards an early time in 1943, perhaps march or april.
The next blurb mentions 8,8 cm Spgr knocking off T34 turrets? Is this possibly related to the one above??
no, it doesnt refer to the one above, its a different memo. Engl. Mk. II is very probably the Mathilda II, judging by 1943 editions of the Panzer Beschusstafel. Both, early T34 and Mathilda exhibited cast turrets, and I know of other memos, which were critical about the resistence of armor castings. This might help to explain why german tank designs preferred RHA welded turrets and used cast armor only for non-structural members, such as mantlets. Personally, I tend to believe that this is not a proof of inferiority of armor castings but highlights the difficulties experienced in the early wartime to make good armor castings. The T34 used 8S steel for turret castings, which are terribly ineffective because this steel was made for RHA and had poor cast properties. I don´t know enough about the Mathilda-II to form an opinion.
MK´s infromation comes in support to what this source states. Backflash when firing Flak ammunition seems to have been a recognized issue.