I’ll chime in with the .257Bob. Hell of an old classic whitetail round. Crosses the magic 100 gr projectile threshold and is pretty damned efficient while maintaining a good velocity. I will second the .357 Mag in a carbine. However, due to its relatively small diameter, I had some issues with terminal performance using cast. Switched to the 158 gr Rem SP jacketed and problem solved. Many deer killed with this combo. If you have to use cast, I would recommend.44 cal and higher, at which point you might exceed your efficiency desires.
