I've seen posts in the pasts where people were excited to find counterstamps so I thought maybe I had something, but it doesn't seem like anyone is too impressed. Fair enough.
They are very interesting and have a story to tell. Sadly, this one is really too generic and may take some time to hunt down some history.
Unfortunately, initials only counterstamps are nearly impossible to attribute because they provide no information to research. I only know of a handful of them that have been assigned to someone or something. Just the nature of the beast. Bruce