I don't know about lions with a .30-30, but Jim Corbet killed several man-eating tigers with a .275 Rigby (7x57). For all I know, our own hunters habit might have as well. Maybe he'll tell us. Anyway the exploits of "Karamojo" Bell are well.dacumented. I believe he killed over 1100 elephants, most of which were with a 7x57.
I would not try to accomplish either of those things with a rifle that light even if it was legal. Those who say that cartridge doesn't matter at all and only shot placement counts are living in a dream world. There who live in flat, wooded country where any shot over 100 yards if long range and likely have never seen a game animal bigger than a white tall, really need to get out more before they lecture other hunters that "magnum" rifles are not useful and only Eastern hunters know anything about stocking.
Sort of a slide thread, but an interesting anecdote. I had a friend (now deceased) that will remain anonymous, that wanted to out-do WDM Bell with his elephant prowess. The friend had taken many elephant over the years with all sorts of calibers big and bigger. He killed an elephant with a 256 Newton, thus using a smaller gun than even Bell.
I asked him how it went on his hunt and his answer was it went without any fanfare. Shot to the brain, dead instantly.
We're fortunate to live in an era where wholly reliable powders exist and the quality of our bullets have never been better. I'd be completely comfortable hunting elephant with any weapon above 40 cal and 400grains given today's bullets. I'd be comfortable with my kids doing the same with a 375HH if I was backing the shot.
But in Bell's era under his circumstances? He made the right choice. The ammo was terribly unreliable and he had numerous problems hunting elephants with bigger guns until he settled on reliable 180gr FMJ solids in his 7x57 and 160gr solids in his 6.5x54MS. They penetrated straight and went bang every time he shot, better than he could accomplish in that era with his large bores.