New Army "Caliber Configuration Study"

[stanc]

P.S. For the sake of calculations, each 5.56 M855 cartridge weighs 190 grains, 7.62 M80 weighs 393, 65G 123gr cartridge weighs 270.

P.S. A weight of 123gr is plausible in a lead-core HPBT bullet for DMR use, but not in a lead-free Ball projectile for general issue.

The Army has already fielded lead-free M855A1, and plans to field M80A1 this year. In the absence of info to the contrary, it's probably safe to assume (for this discussion) that both lead-free rounds weigh the same as M855 and M80.

A lead-free 6.5 Grendel projectile would likely weigh no more than 110gr, which means you can figure a ball round @ ~255gr. Don't penalize the 65G unnecessarily.