thank you David for these nice and useful pics.
this buckle is known to be made by Rudolf Fischer, right ?
There are a few potential issues here.
Firstly and as far as the now well known "oval logo" is concerned, I do not think that this has been positively identified as Fischer. I may be wrong.
In comparison between the nickle silver on silver SS shown here and the pebbled SA (Motor School?) buckle that I also hold and which displays the oval logo, there are some slight similarities. There is the possibility that both buckles share the same pin, pin shroud, claws and C catch. These are however component parts which could have been bought in by any buckle manufacturer.
My two buckles however have a totally different side profile and also, shape and size of ear. If I was making a decision from examining the two buckles that I hold, then I would say that they are from quite different manufacturers.