ORIGINAL: bronko22000

Salt - I'm sorry but the term 'knock down power" is mis-leading. (Unless you hit an animal in the head with a sedge hammer.) What you are looking for is a cartridge that delivers enough energy to provide shock to the muscle, circulatory and nervous system. This shock is the energy transferred from the bullet. Your 30-30 has and will continue to kill a lot of deer every year.
Any cartridge from .243 on up to 30-06 will be adequate.

Good luck with your selection and practice shooting from hunting positions.