Here's how I see it, and I realize this will likely offend a few people, and that is 100% not my intent, so I'm sorry in advance. I'm only sharing my continued thoughts, on my own post by the way, regarding the subject.
My personal philosophy, experience, and preferences do not agree that the nose coming off (petals shedding completely) and leaving just the shank produces better performance than a properly selected mushrooming lead core bullet.
I understand many believe that a caliber size flat and squared-off surface produces more displacement than a more rounded surface. I mean, I can get the idea and thought process that a perpendicular surface will displace fluids out more than a rounded surface.
For example, you can flip over a bucket and pour water onto it and watch that water splatter outward everywhere, right? Now pour water over a basketball from the same height and intensity and watch a lot of the water cling to the ball and run over it. There's a difference, right?
The problem with that though is that's not how it works ballistically. You're not throwing the animal at the bullet. The bullet has to travel through the animal, and is not supported when doing so, like the bucket and basketball are by the ground in my example.
A copper bullet that loses its petals and is left with only a caliber size shank with a flat frontal area is going to typically experience tumbling as the rear of the bullet tries to overtake the front. That's basic physics. The center of pressure will immediately move closer to the center of gravity. The Nosler Partition can behave similarly too when the ogive section meets more resistance than it can handle and only the base of the bullet remains.
A mushrooming bullet has the surface area up front to resist the rear of the bullet coming around and causing tumbling, as well as a better profile for continuing on a straight path (not that it always will). That increased surface area also displaces more tissues as well even though it's more rounded. With a sufficient amount of starting sectional density, there will be plenty of mass still to keep the momentum moving forward and allow for adequate penetration as it produces wounding. An insufficient amount of starting sectional density would result in not enough penetration with the softer/frangible style bullets. That's the main culprit when you see certain lead core bullets fail to penetrate deep enough and over-expand. This is what I mean by properly selecting the right lead core bullet for your particular hunt. Knowing how bullets are constructed and behave helps you to pick the right version and weight for success.
Many hunters don't understand the limitations with lead core bullets and how to increase performance and properly balance expansion versus penetration with them. They don't understand how the different types of construction/composition of them produce, or result in, different limitations and that selecting a heavier or lighter version changes the sectional density and how it behaves upon impact.
Many hunters have simply concluded that you can't get reliability with lead core bullets because so far they haven't, and many others that they talk to, that also don't understand those things, haven't either.
Several bullet manufacturers, perhaps those such as Cutting Edge and Hammer, took that and decided to make their own bullets, and ultimately went with copper to create a bullet that stays together and doesn't over-expand and result in shallow penetration and poor performance (or so their logic tells him).
Like has been shared, evidently what was found and decided, through whatever type of testing, was that the typical copper hunting bullet barely deforms and expands below around 2200fps (some below that), and they in turn don't create much wounding, particularly wide wounding, and thus they kill much slower. This I agree with.
So some manufacturers, such a CE and Hammer, decided to make their bullets hard and brittle (perhaps some more than others) so that the petals would simply break off and that you'd at least have a caliber size surface to create tissue displacement.
Sure, in theory that's better than the minimal expansion you see with other copper bullets that don't even expand to caliber diameter under certain impact velocities, but in my humble and experienced opinion it's not better than a well-constructed lead core bullet, properly selected for the task, and properly placed, and within it's particular limits (sounds like a lot to get right, but it's actually not hard to do).
They think they've made a bullet that's "in a class of its own" and performs superior to anything else, but it just doesn't (again, not in my opinion). It relies almost completely on rapid displacement of tissue and fluid, and that itself is dependent upon adequate velocity versus surface area of the projectile. There's not a lot of surface area with that type of bullet and performance, so velocity needs to be high in order to actually produce adequate tissue and fluid displacement.
While petals may or may not still shed down to 1800fps, or lower, that's still not a lot of velocity left for a good deal of tissue and fluid displacement. Now you're left with the requirement of needing to be more dependent upon great shot placement in that scenario, not actual terminal performance of the bullet. It becomes less forgiving to shot placement errors.
. Explain to me what exactly I've said is outdated and ancient. People get this stuff wrong still every single year, so that tells me it's not been hashed out enough apparently.
