Actually, I suspect that Leibenberg's use of the spherical bushing started with his employment at Pachmayr Gun Works. The late Frank Pachmayr used a spherical bushing system in his Signature Series. Pachmayr's original system was attached to the slide by a large nose piece with a threaded spring cap which was then screwed into the slide's dust cover. Leibenberg then took the bushing system and made it static for the conversions you mentioned earlier. Salassa later picked up the concept and converted a standard barel bushing to accept the spherical ring.
