Bullet weight vs diameter as it relates to stopping power

I like using the TKO (Taylor Knock out) formula, it takes into account bullet diameter. Of course suitable bullet construction is critical.

= Bullet weight (gr) x velocity (at impact) x diameter (inches) / 7000

The higher the value the better.

as an example.....

150 gr 308 = 150 x 2500 x .308 / 7000 = 16.5

180gr 30-06 = 180 x 2600 x .308 / 7000 = 20.5

100gr 243 = 100 x 2900 x .243 / 7000 = 10.0

300gr 45-70 = 300 x 1700 x .45 / 7000 = 32.7

etc.....
 
Google ballisticstudiies.com. And maybe watch The Real Gunsmith on YouTube. Both are very informative. Personally, I lean towards .338 and bigger. Big bullets break big bones. Plus, you can even use cast bullets because they have a whack of energy even at slower speeds.
 
Boomer you are right on on how an animal dies.
Not too many people understand this.
Old timer lou
 
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The unfired diameter and weight of an expanding bullet is meaningless, as it is the expanded bullet that kills the animal. You need a bullet that expands to create a large wound channel. but retains enough weight to penetrate. Therefore bullet construction is even more important than bullet weight.
 
G-Force24 said:
Perhaps in interesting topic.

I have a .308 win, love it for hunting, but I have recently began to think hard about getting something with some more umpf

So here is the topic. What has better overall stopping power, or what makes a bigger difference. Bullet diameter or velocity considering bullet weight would be roughly the same based on availability.

338 Federal with 225gr travelling at 2450 approx fps.
300 win mag with either 220 or 230gr travelling at approx 2650 approx FPS.

My velocities may not be perfect but the point remains, a 308 cal projectile travelling faster, than a wider diameter but slower 338

Thoughts?

Edited, Bullet diameter vs Bullet speed for a faster drop of an animal (moose bear)
Click to expand...

If you have a .308, adding a .338 Fed is going to be a bit redundant. A 300 Magnum will provide a real increase in performance. 300 magnums are pretty good "all around" cartridges.

Even better is to jump right past all the .300's and .338's and get a 375 Ruger, if power is what you want. It's the best .375 cartridge ever introduced, and is fast enough, wide enough and heavy enough.
 
First thoughts, your examples of projectile are off. Optimal for a 300wm is more likely 200-210 gr. The difference in velocity, along with sectional density, is what makes the difference. If your looking at pushing larger projectile at 303 velocity, dont see how that increases reach or lethality.
 
If the OP is looking for more oomph than the trusty 308 than as others of said to see some noticeable effect on game, you will need to either move a bullet a few hundred fps faster than the 308 or shoot wider and heavier bullets about the same speed.

Option A Speed you could try a Big 7.

Option 2 Bigish and Slowish you could try a 35 Whelan or a 9.3x62

Or go Bigish AND Fast and get a big 33 like a 340 338/378 Weatherby 338 RUM etc :)
 
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The way I look at it, the 308 was designed to work with 165-180gr bullets, the 300H&H or Winmag was designed for 180-200gr, the 338WM was set up for 210-250gr. The 338Fed just doesn't seem to be anything that works well in my mind, I've used a 358win, wasn't overly impressed in what it was capable of or it's versatility. If you want more "stopping" power, I don't see it with the 338Fed either. Using a good bullet in the 308 and shooting it in the head or thru both shoulders is what stops stuff on the spot, makes the stop happen real quick.
 
I like heavy for caliber game bullets like the ones made by Rhino in South Africa and by Woodleigh. This provides a smaller bore rifle the ability to produce the terminal performance of a larger bore rifle. For example the 380 gr Rhino bullet fired at 2300 fps from my .375 Ultra, expanded to .92" and penetrated about 30", the .500 Nitro's 570 gr X bullet fired at 2100 fps that killed by African buffalo, penetrated about 30" and also expanded to .90".

A heavy for caliber bullet designed with a solid copper shank, and a pure lead core that's bonded to the jacket, even at moderate velocity upsets to a very large diameter provided the target density is sufficient for the design parameters of the bullet. Penetration of heavy for caliber bullets tends to be better than lighter-faster bullets and since the bullet can't break what it can't reach, particularly on a rear quartering shot, a more significant wound is the result. Provided a rate of twist that will stabilize them, bullets with long bearing surfaces tend to shoot better than shorter bullets in rifles with worn throats. Since heavy for caliber bullets are normally fired at moderate velocities, round nose or semi-spitzer designs are no disadvantage when range is nominally 200 yards, but being shorter than bullets with long range profiles, are useful in rifles with normal rates of twist. That said, all game bullets tend to penetrate deeper when fired from a fast twist bore due to a shorter precess time at impact.
 
Velocity and energy are not the key to stopping an animal. If velocity and energy were the answer, an arrow wouldn't be able to kill. Damage to vital organs and being able to penetrate to them is the key. Low velocities with heavier BC bigger SD bullets kills all the time. 500 yards with a 143 ELDX from a 6.5 CM will easily kill sheep, deer, etc. A big heavy animal may require better penetration achieved through bullet construction and velocity, hence why a mono bullet at high velocity is so effective on large bears, big bull elk and the like. Then on top of all this is placement. Put an insignificant bullet in the heart/lung area, the animal will die. Hitting a shoulder bone with a light bullet at low velocities may lead to poor performance of the bullet and a wounded animal. The more critical consideration in my opinion is the shooter knowing the capability of the chosen bullet over the chosen range envelope the shooter will shoot, combined with shooting within the shooter's ability to put the bullet where it needs to be placed. Stay within those constraints, you will be a successful hunter (assuming you find game!!).
 
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Maybe some confusion between "stopping" and "killing". So far as I understand the "stopping" scenario is something enraged coming hard at you and it must be stopped, before it can engage with teeth and claws, or simply trampling right over you. Might be faintly related to an animal about to get away into difficult retrieval terrain. It may already be heart shot, and can be "dead" in 3 or 4 more seconds, but you won't likely survive until then, unless you "stop" it. Strategies include breaking shoulder bones to make it fall, or CNS hits to make it expire / paralysed in mid stride. Big, heavy bullets do better in either - the CNS strategy is all about penetration and placement. A heart or double lung shot is not a "stopping" shot, even though it is a "killing" shot; a brain or spine hit almost always is.
 
I have shot 20+ moose and 20+ elk. No question, elk are tougher and are less impressed with the gun you bring. Moose can easily be dispatched with common deer calibers if you shoot them in the lungs. Stoutly constructed bullets are always a plus. Elk can also typically be a long-range proposition. That is where the big magnums shine. But, all that being said, it is shot placement that wins the day and brings home the meat for the freezer. If a person gets a big gun thinking it is the solution, but cannot shoot it well enough to put one in the boiler room, then go back to the .308.
 
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