I don't recall all the details on it but there was an intermediate round between the old .22 WCF & the Hornet, with almost identical dimensions to these. It was developed in Germany as I recall for use as the small caliber in the 4-bbl combo's & was often used in singles, drillings etc & was known as the 5.56x35R Vierling. Best as I recall this round was only loaded to a max velocity of around 2,000 fps, much lighter than a full Hornet load. I have a really neat little Geco scoped single shot bolt action with a cracked receiver at the lug seat, which was no doubt built around this lighter load & subsequently used with Hornet loads.