Alternative to 6.5 Grendel?

[JASmith]

Going with dense, hard metals helps a lot for both effectiveness and keeping the length short and demands on twist rate within reason.

Here is an example that many of us have probably looked at over the last couple of years. This could be implemented in a 6.5 caliber rifle cartridge with, perhaps, a sightly longer and larger diameter sliver, but still with impressive velocities:

http://www.gotavapen.se/gota/cbj/cbj_crtg.htm

I've done the math, and that tiny tungsten sliver indeed has a very similar momentum density to that of the 7.62x51 ball round, but is a lot harder. The added strength helps explain why it does a tad better.