I have no idea what "perfect" is, but a choice that would give me full confidence is the old 9.3x62 with the classic 286 gr. bullets at 2400 fps. I'm pretty sure it will kill any plains game reliably and even though it is not fast, it will have a flat enough trajectory for most situations. I just choose not to shoot at any game that is over 300 meters away. I have experienced several light, fast bullets do enough odd and unpredictable things after striking game that I'll choose the reliable penetration and bone breaking power of a bigger, somewhat slower bullet that always hangs together and is not overly challenged by passing through a humerus bone on the way to the vitals.