Hatsan makes a pretty good break barrel .30 cal
https://www.youtube.com/watch?v=39R3gjG3exs
more than enough power to take down game animals, and pretty accurate too-
if you ant to go for the air cannister ones, then these FX ones seem to be pretty well in reviews
https://www.youtube.com/watch?v=iucATtbtfwc
Amazon actually sells a number of larger bore pellet rifles- and any number of sporting shops sell them too-
Was just looking at a couple Hatsuns on Pyramid Air.