Optimized Caliber

[stanc]

The 6.5 Grendel's genius is the performance it gives from weapons currently sized for the 5.56 cartridge. One could, I suppose, make a pretty good case for the 65G as is, in terms of performance relative to size and recoil, even with a blank slate. And it's a case I'd be tempted to make if I had a fully developed 6.5 Grendel M855A1 analog.

Unfortunately, such a critter doesn't exist, and in any event, you most likely don't have any M855A1, either.

But, since performance should be relative as long as the same type bullets are used in each caliber, you ought to be able to make your case (if the premise is valid) via comparative testing with lead-core FMJ bullets in 5.56, 6.5 and 7.62 ammo. There's no need to wait for a 6.5 M855A1 analog.