I saw this one on Gabe Suarez' Warrior Talk Forums.
http://www.thetruthaboutguns.com/2011/05/chris-dumm/lever-action-ballistics-30-30-vs-357-magnum/
The .357 almost gets to the .30-30, but not quite. Within 100 yards, though . . .
Good article.
There are really three phases of ballistics:
1 - Internal ballistics: What goes on from the cap being busted until the bullet leaves the muzzle, such as max pressure, pressure curve (Rather different for rifle vs. pistol powders), rifling rate of twist, muzzle crown effects, etc.
2 - External ballistics: The bullet in flight, such as muzzle energy in ft-lbs., velocity, gyroscopic stability of the bullet, aerodynamic effects, etc.; generally a smaller-diameter bullet has an advantage here. But, given that muzzle energy is a kinetic energy measure (MV
2 * 1/2), velocity counts for a very great deal in this measure, which may give a somewhat false impression of the final effect on target, due to the third element -
3 - Wound, or terminal ballistics: What happens when the bullet actually hits, particularly how rapidly the bullet transfers its remaining energy to the target. Absolutely meaningless in shooting at paper or through chronometer, but the essence of defensive or game shooting. A great deal depends on bullet shape and expansion characteristics here, and narrower-diameter bullets have a disadvantage because the same aerodynamic reasons that help them keep velocity apply to the hydrodynamic environment of the wound, i.e. they expand slower, making a longer but less-disrupted wound cavity. In my own experience, there ain't all that much to a deer's chest, and it's all too possible for a rifle bullet to go completely through the SOBs without putting them down.
Still, the biggest advantage of the .357 is that you can pack a sidearm that takes the same fodder, which is not so critical hunting but could easily be life-or-death in a survival situation. The ammo for both the .30-30 and .357 is ubiquitous, of course the .357 does have the advantage that you can fire .38 Spl out of it in a pinch, which is if anything even more common.