http://www.airgunforum.net/agf/index.php?showtopic=1527

This shows the pictures of my BSF's with a catalogue from the late 1970's.

Ian - I also have a 1958 parker hale catalogue with some BSF's in (54 and 60)

I suspect the 65 was either confined to the home market in Germany rather than the US, or a model that was quickly discontinued. Yours has an adjustable trigger screw in the end cap I seem to remember so may be this was a prototype ?