Troy,
Your friend should buy some 130 grain Norma VLDs and examine them closely. They have an extraordinarily small meplat and the jacket thickness is much greater than the MatchKings and such, although the jacket material is probably very conventional in terms of its composition and hardness. Their core is most likely a pretty conventional lead, not a hardened alloy. They leave a very small/tight bullet mark on the ram even when driven at very high velocity which I have interpreted as the bullet "staying together" better upon impact.
Cauterucio bullets also use a thicker than typical jacket to good advantage. If you examine the Norma bullet very closely you will see that it is not a "true" VLD design in that the very last portion of the ogive has been changed around to a somewhat more rounded design which has been demonstrated to result in better grouping between 600 and 1K yards than the original VLD design used. It made no appreciable change in the B.C.
The 130 grain bullets are on the light side for rams as they need to be driven quite hard to get the velocity necessary to obtain the momentum equal to some other bullets, but they are very definitely "hitting harder" than most other bullets. Achieveable velocities start dropping rather quickly when the bullet weight gets beyond 141/142 grains, especially in magazine rifles. There are some 147 grain bullets which are reported to shoot well, but are not able to obtain sufficient velocity to warrant their use in a magazine length loaded 6.5-08.
There are some 136 grain VLDs made by E-Zee-Tens which have shown some promise in the 1K yard events. I have not yet done testing with them, but it is probably a weight that would be easy to achieve, even with a thicker jacket and harder (less dense) core while keeping the length of the bullet within the current dimensions known to work well with eight twist barrels. Your friend will probably want to do some experiments changing the cores to adjust weight in the same jacket to hunt for the "sweet spot" of velocity and retained energy for magazine length loads.
As you know, the VLD designs require chambers with special throating to shoot well when loaded to Rem 700 short action magazine lengths, whereas the Lapua 139 grain Scenars shoot very well out of a great many different chambers/throats, which is something to consider when choosing a bullet design. The 108 grain Scenars seem to be much easier to get to shoot consistently than the 107 grain Sierras. The 123 grain Scenar is a pretty decent bullet as well.
I am not terribly certain that changing the alloy of the jacket to a harder alloy is all that good an idea as there are a great many unanswered questions which arise when doing so, quite apart from the problem of obtaining the raw materials which might well be difficult, if not impossible, at a practical price in the small quantities involved. Everything from ease of manufacture (and wear on the forming dies) to gas sealing in the barrel and, of course, barrel wear. I think that simply using a thicker jacket, harder core and small meplat would accomplish the desired objectives and avoid confronting these unknowns, but that is just an opionion.
As far as the 142 grain MK goes, it shoots well enough, but does not do well on the ram if the muzzle velocity is much above 2750 fps. The 139 grain Scenar can be driven appreciably faster before encountering bullet failure on the ram. The Cauterucio bullets seem to tolerate whatever velocity you can achieve, as will the 130 grain Norma.
