Gary,
We find that change pretty often. The world is full of 22 Hornets, but 5.5X35R Vierlings are getting scarce. Other than the higher pressures, the main problem with the conversion to 22Hornet comes in combination guns where there is a second rifle barrel involved, mainly, but not exclusively, Vierlings. The two different caliber barrels were regulated to "shoot together", but modern Hornet ammo has a very different trajectory. For single shot rifles the "fix" is usually adjusting or replacing the sights, which is considerably easier than re-regulating Vierling barrels. The change to the sights may have already been done. Handloading to 5.6x35R specs also works, but if that was an option for the previous owner the conversion may not have been done. Have fun.
Mike
