New Army "Caliber Configuration Study"

[stanc]

You rather missed my main point, which was that a military-standard 7g lead-free 6.5mm bullet could perform quite close to an 8g lead cored equivalent in terms of velocity and energy retention plus wind-bucking ability, and distinctly better than the M80 in these respects.

Oh, I fully understood your point. I was just noting that your charts don't tell us how 6.5 Grendel would compare in that regard.

Anyway, the muzzle velocity I assumed of 800 m/s for the 8g bullet is actually close enough to what the Grendel can achieve (777 m/s for 8g from a 20" barrel - a reduction in MV of less than 3%) to make a useful comparison.

The comparisons we are making here are with the 7.62mm weapons, since it was John's comment about that I was responding to.

No, you are not comparing the weapons, because they do not all have 20" barrels, and it's arguable as to what barrel length GPC weapons would have.

You are making an academic comparison of the cartridges under an artificial restriction (equal barrel lengths). This methodology is used in order to show one's pet cartridge concept in the best possible light, but it seldom provides a realistic comparison of the cartridges in the barrel lengths actually used on the battlefield.

In John's hypothetical ambush scenario, he discussed 65G ARs and LMGs. The current US Army individual weapon is the M4 carbine and the LMG is the M249, both with 14.5" barrels. The USMC's M27 IAR has a 16" barrel, as does SOCOM's Mk46 LMG. Therefore, in the best case scenario, I see 16" as the maximum likely barrel length for 65G weapons.

Which means the question that really needs to be answered is how would 6.5 Grendel (7g/108gr bullet) performance from a 16" barrel compare to 7.62x54R in the 25.4" barrel PKM?