Something that pisses me off. The TSX does NOT have the same frontal area as other bullets. You cannot simply measure the outside of the petals and call 1.5x expansion "Frontal Area" See those gaps between the X pattern?? Those gaps REDUCE the frontal area (and potentially reduce wound diameter) so you can get INCRESED penetration. That's how and why it works so well for penetration.
This assessment completely disregards the rotational velocity of the bullet. The speed of rotation is diminished only slightly during the bullet's time of flight. If your rifle has a 1:12 twist and the bullet exits the muzzle at 3000 fps, but the bullet has a rotational speed of 36000 revolutions per second. If you have a fast twist barrel, the rotational velocity could be as much as 61714 ###, if your barrel has a 1:7 twist. Given the rotational speed, the air space between the petals would for all practical purposes not exist until the rotational speed had slowed to nearly a stop. The faster the spin, the deeper the bullet penetrates because less velocity is lost through precession, which is the yaw a bullet experiences when it hits a barrier of different density, such as a game animal. The faster the rotational velocity, the faster the yaw is corrected. This has been proven in tests comparing bullets fired from fast and slow twist barrels, resulting in consistently deeper penetration with identical bullets fired from the faster twist barrels. Precession occurs twice during the bullet's flight, first when it exits the barrel into the open air (this is what target shooters refer to as "going to sleep", which is seen as a bullet being more accurate down range, once it has "gone to sleep" than it is at close range) then the bullet precesses again when it impacts the target.
If the theory of supercavitation is correct, and I think it is, when a bullet passes through a fluid target medium, a shock wave moves ahead and off the sides of the expanded area of the super sonic bullet. We can see the shock-waves that we see come off a bullet in flight when captured by a high speed camera. Except now during the penetration of the target, the nose of the bullet has expanded, and the shape of the shock wave has changed from the way it appeared in the high speed photo. Now it projects a concentrated shock-wave a small distance ahead of the bullet's flat nose, comes off the edges of the expanded nose of the bullet, and neither the tail of the bullet nor the shank produce a shock-wave. The only tissue not effected by the shock-wave is the hide and bone, all fluid bearing tissue is crushed and displaced while the bullet's passage is supersonic. The only material the bullet actually touches inside the body is bone, so those razor sharp petals don't even come into play until the velocity is reduced to subsonic. When a frangible bullet goes to pieces inside the game animal, I will admit I have no idea of how the mechanics of the wound volume occur, but in extreme circumstances the wound volume can be very broad if shallow. Small bore high velocity varmint bullets provide the best example, and there is no doubt that if this can be arranged to happen within the chest of a big game animal it goes down pretty quickly.
I observed a huge wound volume when I first tested the 380 gr Rhino bullet fired from my .375. That bullet expanded to nearly an inch with an impact velocity of 2300 fps, 500 fps slower than a 270 gr bullet, and 300 fps slower than a 300 gr bullet. Due to the heavy weight of the 380 gr slug and the high velocity of the 270 and 300 gr bullets, penetration was dead even at 32", and the ballon shaped part of the wound that is created by the supersonic passage of the bullets was also equal in length, showing that the lighter bullets gave up velocity at a faster rate than did the heavier bullet. But the wound volume of the 380 gr bullet was larger by a multiple of 3, which is a guess because it caused the container holding the test material to fail. That is the difference between a bullet that expands to .73 and one that expands to .93 despite a large difference in velocity.
Game animals are not a homogenous test medium. They are a complex blend of tough elastic skin, suspended organs, air filled spaces, and a variety of bones of different sizes and densities. A game bullet has much to overcome, and hunters over time acquire a preference for how a bullet should perform. I like to see bullets exit. If the shot is not immediately fatal, two holes let out more blood and make tracking easier. I prefer bullets that shed little of their original weight, because to my way of thinking, you might not always get that text book broadside shot that favors the frangible bullet, and in those circumstances penetration trumps a shallow wound cavity. In my experience the game is more often than not quartering to me, and the number of times I've had the picture perfect broadside shot is about even with the number of times I've had a head on shot or a going away shot (which I will only take on a wounded animal or in a dangerous bear scenario where the bear has to be stopped immediately).