you can pretty much shoot anything with any weapon for stone knights i would go with shotgun or elephant gun (if have) just keep dodging attacks

u must use the flying creatures to your advantage. when they get ready to dive in for a attack use the stone creatures as wall to block. the flying monsters will kill them 10 times faster than you can so use them wisely. hint! when the monsters dive make sure that u are in a position were they can take out 3 or 4 knights in one dive.