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Originally Posted by Stinky Coyote
Great read! Confirms everything, not sure where you’re headed with this?
As I said elsewhere, there is an exponential factor in penetration, the faster you hit something the faster it slows down in proportions far greater than the difference in velocity, momentum etc. Heavier arrow with same momentum will be going slower than lighter arrow with same momentum. So the lighter arrow doesn’t go as deep because it was met with 7x the resistance due to added velocity.
My terminology for same thing is...faster you hit it faster it stops, slower you hit it slower it stops.
So same arrow momentum went deeper with heavier arrow. Same momentum means same energy, or same bow or same cartidge two different bullet weights. The heavier one goes deeper even though slower...because it’s met with less resistance AND it’s heavier for same frontal area...higher sd. And since we talk about impact velocities same that rules out momentum as a useless figure. Over and over proven that something like a 6.5 Swede with 160’s and approx. .33 sd will out penetrate just about everything else with much higher momentum figures. Because momentum doesn’t mean anything. The is a threshold and efficiency in high sd bullets at certain velocity ranges that work beyond expectation or even belief. We covered this before, momentum isn’t a factor you can count on. It’s there but it doesn’t matter, that’s all it’s got. When those two arrows from same bow and the slower heavier one goes deeper, it does so because it’s higher sd. End of story...for the twelfth time.
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One factor has yet to be mentions, that being, that in some cases, a higher impact velocity can actually result in a smaller frontal area, which results in more penetration, but a smaller wound channel. I have seen cases where the jacket folds back tight against the shank, instead of creating a large mushroom. This results in a higher S.D. as the bullet passes through the animal. I have seen this using the 257wby, 7mmstw, and the 300rum. This is just one more reason why you can't use numbers to accurately predict penetration.
The simple fact is, that a person could use pretty much any cartridge with a bullet from .264" on up to successfully harvest moose, elk and deer in almost any situation. I have owned cartridges up to the 375H&H, but these days I don't own a cartridge using bullets larger than .284" . My go to cartridge is still the 7mmstw as it has been for nearly 30 years, but that is more about having used that cartridge or so long, and being so familiar with the ballistics , than it is about needing a magnum cartridge to hunt the game that I hunt.
As to these silly comparison threads, what is next, a 6.5x300wby vs 50bmg thread? These threads are about as foolish as the threads where people found it necessary to post silly drawings to try and prove why their favorite cartridge is superior. I had to laugh when drawings for wildcat cartridges that are not even standardized, were being used to demonstrate why one cartridge provides a better seating depth for a given bullet, than another cartridge. And then the poster ignored the larger case capacity that one cartridge offered, which enabled it to produce more velocity at the same pressure level.
The bottom line is that drawing and numbers are just that, they can't accurately predict how a cartridge will perform on game, or even on paper at times. And with today's bullets, S.D. of unfired bullets really doesn't mean a great deal when predicting performance on game.