Safarischorsch:

500 Jeffery does not equal 500 Schuler!
Historically likely both derived from Schuler as designer but the earliest Kynoch drawing differs from the earliest Schuler drawing and based on this CIP have accepted the 500 Jeffery as a separate cartridge from the Schuler.

Further: Harald Wolff's 500 is an "improved" cartridge without the rebated rim. Different to the original 500 Jeffery. The Wolff cartridge was designed specifically with the feeding issue of the rebated rim in mind.