Grendel as a Universal Infantry Cartridge

[stanc]

My thinking on this subject has been gradually evolving. I'm now inclined to think that while 6.8x46 may be about right, the case diameter should be wider than the 6.8x43, for two reasons: the need to accommodate significantly longer copper+steel bullets, especially tracers, which will occupy more of the case capacity; and the desirability of allowing for the future use of part-polymer cases, which may have thicker walls than metal ones, thereby further reducing propellant capacity.

Okay, to meet all of those needs it looks like the .445" diameter case of the 7x46 UIAC is what will be required.

Next question: Is it better to just push for 7mm UIAC, since that cartridge (and a 7x46 GPMG!) already has been developed and there's some data for it? Or is it worth spending the time (and money?) to "study" the possibilities of 6.8 and 6.5 versions?

Since the 7x46 info says (with a 130gr bullet) it has 7.62x51 muzzle velocity, is it likely that a 6.8x46 w/120gr bullet and 6.5x46 w/110gr bullet would have approx the same MV? Or would 6.8 and 6.5 loads need even lighter projectiles to match MV?