hmm, after thinking in it for a while i remembered a couple that might fit the bill. first off, as a few others have said already, springers are generally pretty quiet. the talon ss is a pcp rifle, but has a barrel shroud that dampens majority of the "pop" when fired; the logun s-16 fac is very similar. basically, if you want a non-springer look for one with some kind of barrel shroud; it is pretty much a legal silencer. or, you could buy/make a silencer for whatever air rifle you want to use, and pay $200 to get it licensed with the atf. you have lots of options. some people have even made their own barrel shrouds; these are perfectly legal without any kind of license.