I'm glad a .264 Win Mag doesn't have KD Power

Hit him in the spine, I'd guess. I saw exactly the same type reaction from a Buck I shot in the spine with my 220 Swift many years ago.

He's waiting to be field dressed.

Knock down power means "Squat" if you don't hit them in a good place.

Hydrostatic Shock is the Key

Localized trauma caused by good bullet placement is extremely important. Hydrostatic shock though can create damage to the central nervous system, mainly the brain, far away from the actual bullet impact area. It does this by causing a sudden, violent increase in blood pressure. This pressure wave travels up the cardiovascular system to areas throughout the entire animal, including the brain, rupturing small blood vessels.
The effects of hydrostatic shock vary on the size of the animal. That's why you may see a small deer go down very quickly, way faster than could be attributed to the local trauma, and a big elk or nilgai run off after a hard hit right in the boiler room.

I've gone smaller with my rifle. Now use a 6.5 Creedmoor or 25 06. Drops em every time. Don't understand the need for a 300 win mag for Texas whitetails. But, if guys like it, use it. There isn't one perfect cartridge

Place a paper plate over vitals, hit the plate, deer will drop.

Shot placement over caliber.

This, except mine are 6.5CM and 6.5x55

Agree 100%!

Really of all the follow ups to this topic no one quoted this one!!

I know if a grizzly was charging me and a I had a 223 and a 300 mag near me I would choose the 300 mag. As far as the physics part of a actual knock down power I don't know but I would think it has something to do with sectional density of the projectile and the rapid absorption of energy the animal receives when its hit with a bullet traveling 2000-3000fps in which case the bullet maintains inside the animal.

I want both. Shot placement up the front leg in the shoulder. Largest area of mass that can accommodate a poor shot. That is why LEO's are taught that if they are going to shoot a bad guy it is in the middle of the chest. Not the leg, not the neck - the largest area that can help account for a poor shot or a gun that is off.

The above coupled with a 180 grain bullet will do the job most every time. It may be overkill on Texas deer but if I am going to take a life of an animal I want to do everything in my power for it to be a clean kill - if I ruin some meat in doing so then so be it.

Last of all we should all try to shoot within our ability and within a range that we are relatively certain we can make the shot. Just my old school thoughts from almost 60 years of hunting and shooting.

But it's tough gettin' ' em to stand still while you place a paper plate over their vitals.

"...if I ruin some meat in doing so then so be it."

I have to kindly disagree with this statement (to an extent).

I don't think there is anything wrong with having a deer run 50 yards and then falling over dead but i'm also in the category of thinking a .223 is fine for (my) deer hunting.

Knock down power is super important, but I don't like ruining 1 shred of meat, so I aim for a big branch above the deer's head.

243 doesn't have the same lumberjacking ability as my 7mag.

How can y'all debate a concept that has no real definition?

"Knockdown power" is just a phrase some magazine writer came up with years ago to make an article interesting. It's essentially meaningless.

My .6mm doesn't knock them down. However they do fall down from being shot in the correct place as they are dead.
Works every time.

^^Bingo!^^

22, 6mm, 6.5 mm, .277", 7mm, .308", .338", .375", .44", .45", .50"

The guy that shoots any one of those extremely well, will kill stuff.

Knock down power, kinetic energy, I don't know what you want to call it. Ive seen a few deer shot in the guts and unfortunately shot a few in the guts with 270 Winchesters and 30-30's, they all either died on the spot or ran a very short distance with a nasty trail to follow. Have seen one deer gut shot with a 223 and my favorite 60 grain nosler partition. It killed the deer and we found it within hours but it was a very long sparse trail I wish I would have had a dog to follow, at several times we lost the trail and resorted to spreading out before we picked it back up again.

You don't need a cannon, but I am still a firm believer that more bullet, more gun, and more energy is a positive thing for when shots go wrong.

. I should have clarified. The statement about ruining meat was meant to compare a "safe" shot in the shoulder versus neck shots. Also I use the higher grain load because the deer we hunt are large animals. And if it is a trophy animal I want to do all I can to drop him where he stands. Works for me

Nothing to criticize.....doesn't say what brand!

.6 mm seems small. Kind of like .9 mm. Now, 6mm, that will probably work.