Phil

The sight you describe as a "Walther Sport", was not a Walther sight, all Walther sights from early days to current ones have a clamp similar to the ones on the LGR set Bob sent you. All Walther sights old and new, are compatible on old and new Walther dovetails

What you describe is an Anschutz 6700 series sight, they used that clamping method for many years, and on any thing, even Anschutz's, it was common to see people trying to pry them apart with a screw driver to get them off! The common mod with them was to saw off the front half of the clamp so it was just on one thumbwheel and less bend so they still clamped OK but came off easier!

Have Fun
Robin