You're thinking too small. A .357 میگنم, ماگنم could take out nearly any modern creature, except those with natural armor. I would need a رائفل for anything armored. Problem is, some dinosaurs were much much bigger than any modern animal, and some had natural armor. But yes, a 357 میگنم, ماگنم would take out a Herrasaurus.
...*thinks of Skyrim trolls* they're really a pain to kill when you're a low level, but once آپ reach a high enough level, they get pretty easy to kill.
Erhm...well, if they're just annoying and stupid, I really hate them. If they're good at what they do, they're still annoying, but I'd respect that. Kinda like "You amazing bastard."