45-70 vs 300win mag
observations regarding the 300 Magnums and the 45-70 are a classic example of what is wrong with kinetic energy generation as a measure of effectiveness. The kinetic energy equation squares velocity but does not square bullet weight, thereby "prejudicing" the results towards those calibers that drive relatively light bullets to relatively high velocities. However, when one calculates power by giving equal value to velocity and bullet weight, as in the momentum measurement, the results are totally different. For the sake of this discussion, lets use modern 45-70 ballistics. As reflected by one of our loadings, the 45-70 can drive a 415-grainer to 1850-fps (from a Marlin lever-gun), producing 3150 ft/lbs of kinetic energy and 110 lbs of momentum. The 300 Winchester Magnum drives a 180-grainer to about 3085-fps for 3800 ft/lbs of kinetic energy and 79 lbs of momentum. It now starts to become clear that the manner of measurement tends to determine the outcome. Also, with the various 30 caliber guns it is essential to use expanding bullets in order to effect a clean and quick kill, whereas with the 45-70 bullet diameter is so substantial that expansion is not required to kill cleanly. When one goes to non-expanding bullets, the penetration depth achieved is much greater than can be achieved with any expanding bullet from any caliber. Indeed, about the most penetration that can be achieved in wet newspapers (a common test medium) with premium expanding bullets in any caliber is about 18-inches. With the 45-70 and proper hard-cast bullets, penetration depth can range anywhere from 36-inches with the lighter castings to 70-inches with the heaviest.#
High velocity guns shine where long-range shooting is required. However, when the game is extremely tough the various 300 Magnums leave much to be desired, tending to over-expand and invariably producing shallow penetration channels.#
A properly loaded 45-70 will shoot lengthwise through anything in North America, something the various high velocity calibers simply cannot do or even come close to.
GCI Ballistics