Addendum.....
FWIW;
Several years ago I had a GunDigest,loading manual, or some such publication discussing this issue. It had some high speed X-ray photo-micrographs of a Sierra soft-pt and a bullet much the same as a Speer MagTip or a Rem. Cor-lokt (gettin too old to remember which!).
The tip of the Sierra had "slumped" due to the inertia and friction heat of acceleration and barrel passage that showed the tip of the bullet almost flattened to the same degree as the "mag-tip" bullet.
These factors partially explain why the tip deformation is not as significant as might first be imagined. Also explains why Speer's flat nose .30 caliber bullets have such a high ballistic coefficient as compared to many other such bullets. They (Speer FN's) have a "spitzer" type secant-ogive with a smaller exposed lead area- both thickness and diameter.
The other part of the explanation is that with a properly designed spitzer style bullet, the center of gravity is in the rear part of the bullet and the small deformations in the nose are closer to the center of rotation and away from the center of gravity.
Additionally, with super-sonic objects, the frontal shockwave propagates from the front such that it negates some effects of the tip irregularities.
All these explain why the plastic tiped bullets "behave" so well.
(The plastic tips actually have higher strength modulus and melting temps than lead. If you don't believe me, look at the tip after recovery from a game animal. I have some from 100gr Nosler .257's, and one from a 35gr Horn. V-max from a .22 Hornet @ both at 3,150fps m.v that killed a doe DRT from a heart shot that look almost as if they could be reused! -of course the jackets and lead cores essentially disintegrated.)