I "might" have a 5.6x35R Vierling. Some time back, I bought a Husqvarna single shot, bolt action advertised as a ".22 Hornet". I'm a bit nutty about the cartridge and maybe more than a little nutty about Huskys so I slapped a bid in and eventually won the auction. Of course, then was the perfect time to do my research. Husqvarna never built a bolt action, single shot chambered for the Hornet.

Further research leads me to believe that some unknown 'smith converted what turned out to be a Model 365 into a central fire ignition, added a second recoil lug and an appropriate extractor and chambered it in what appears to be 5.6x35R Vierling.

I had a machinist friend shorten the rims (from the front) to the Vierling and proceeded to load up some 40gr. lead slugs over modest amounts of Unique. Results were dismal with bullets keyholeing in very short yardages. At least the cases were fireformed.

I shelved the endeavor for a bit but want to get back to it "toot suite". I'll load up some more a little faster and a little slower to see if I can get some round holes.

Not much help to the original poster but, hey, you're not alone!

Cheers!