If Speer lists data for a bullet designed for hunting where they push that bullet past 2200 fps in lever guns, which link I posted for you, that bullet is designed for impact velocities far higher than can be achieved in the 44 Mag. If a guy says they exited from impact velocities exceeding 2000fps, they did fine. Would you consider it better performance if they didn't exit? The only way that is happening is if the bullet fragments significantly.
They also list their 240gr bullet at those velocities, but I think that most would be concerned about how a bullet designed to open properly at handgun velocities would do so effectively at a velocity nearly 50% greater and also vice versa.
If I recall, handgun bullets at higher velocities was one of the original problems of the early 444.
Hornady's 35 cal FP designed for 35 Whelen and other similar velocities but will only expand at the highest velocities >2000fps achievable early on in the trajectory from a heavy loaded 35 Remington. Around or under that 2000fps it almost universally fails to expand. Yet load data exists for that bullet in the 35 Rem. Similarly the soft 200gr RN core-lokt bullet, designed for the 35 Remington, is likely over matched by the velocity achievable in a 35 Whelen. Therefore I do not consider the mere presence of load data as meaning a bullet is adequate.
But I think you might be misunderstanding my question. I was looking to use the 270gr in 444 marlin not 44 mag.
To answer the question "Would you consider it better performance if they didn't exit?" the answer is, maybe. If the bullet doesn't exit that means that all energy in the round was fully transferred to the target. But thinking about it, the 444 round has a lot of energy, which likely exceeds the energy requirement to pass through most animals under the 800-1000lbs mark. Put another way it is unlikely any bullet would be retained on deer sized animal, or most hogs. Even a 444 solid (or 45-70 for that matter) will create a substantial would channel and mortality just by nature of its caliber and energy, even if that energy is not completely transferred to the target (IE, by the bullet continuing to pass through the animal after good shot placement). But on that game it is still quite effective.
If it did not pass through, all that energy might result in substantial tissue damage, though that more relates to a velocity higher than that achievable in the 444.
Information I acquired from another site illustrated great penetration of the 270gr Speer, but 30+% loss in retained bullet weight, which tells me it is either fragmenting or sheering pieces of lead off as you mention. The author came to the same conclusion. 'Note, with many bullets the 44 Magnum outperforms the 444 for both penetration and wound cavity. Believe the 444 velocity exceeds the ability of the bullet to retain ideal terminal performance, generally giving up 20% more bullet weight...'
The Hornady 265gr retained nearly 100% of its weight in the same test. It is a very tough bullet, as mentioned, designed for 444 Marlin Velocities. If I was using it for large or dangerous game, it would be my preference over the Speer if it was still available. In fact in just about any scenario I think I would prefer it, since on lighter game anything is going to overpenetrate anyway.
I appreciate all the info because static tests and data don't tell the whole story and I want to pair it with real world data.