Thanks for the URL that does the calculations and John's notes.
: My own findings, and beliefs are that the old-style bullets benefited from higher SD numbers, which seems directly co-related to their penetrative power. This seems to be true, whether they were lead, an alloy of lead, or jacketed in nickle or some other alloy with a soft lead core. Bullets were pretty much round nosed soft points, or flat noses and preformed pretty much the same in regards to any differences in compostion. Greenhills formula seemed to work and was adopted. Was it perfect, not precisely, but it worked and is just fine today, with a simple adjustement.
: Newer bullets, the Premium Bullets if you will, have changed the way bullets penetrate and hold together. Even simple bonding has changed the way bullets penetrate, but composition to a great extent, determines their length, which directly effects stability.
: Stability in the air, has literally nothing to do with S.Density, and all with length & it's rate of spin - always has. With the old style bullets, SD was mainly directed at how a bullet penetrates, not with it's gyscopic stability.
: The the ctgs. as noted above, pure lead or an alloy is used, and the Greenhill formula works pretty good, that is, if you subtract an inch or two, it's precise enough.