Anyone knwledgable about large/interesting caliber air rifles...

Apart from Quakcenbush (beautiful but difficult to get hold of) and Chinese or korean (not so sure about the uniqueness), are there any good large caliber air rifles out there? Age is not too much of a problem (nor FAC status), it would be nice to get hold of something (very or reasonably) old, but it would also be nice to get hold of a modern one, even multishot, basically something with nice engeineering.

So anyone know of any peculiarities out there?

tim