US Army Considers Adopting an Interim Battle Rifle in 7.62NATO: eventually adopt 6.5

[stanc]

LR, solid argument.

What this says to me is that IF a military was to institute a cartridge other than 5.56, THEN it doesn't necessarily need to be more than something like 6.5 Grendel. For example, it wouldn't need to be the .264 USA with an OAL of 2.60. In the "real world," grunts can rarely use its extra range relative to its extra weight and bulk.

Whether or not a military should adopt the 65G is a separate question, but what your analysis says to me is that they should NOT adopt something like a 264USA for the standard carbine.

I agree that something like 6.5 Grendel makes more sense as a carbine round than .264 USA, which is unnecessarily bulky, heavy, and powerful for the task.

However, the .264 USA seems intended to not solely replace 5.56 NATO for carbines, but also to replace both 5.56 and 7.62 NATO for all shoulder weapons in the platoon.

If a one-caliber system is desired, 6.5 Grendel seems a bit underpowered for the MMG role.

Devil's Advocate question: Does your analysis also argue against the necessity of 7.62 NATO in a medium machine gun? Side-by-side, what does a 762N MMG in a mount do in a beaten zone at 800m, for example, that a theoretical 65G LMG in the same mount at the same range with a 123gr VLD FMJ doesn't do? (Here I am assuming very similar external ballistics to M80.)

A few observations:

1. Beaten zone is not the only performance criteria for machine guns.
2. A VLD shape may not be a viable configuration for a military bullet.
3. The lead-core FMJ is being superseded by the lead-free EPR design.

An EPR projectile for 6.5 Grendel seems likely to be significantly lighter than 123 grains, which will affect trajectory, wind drift, effective range, beaten zone, and terminal effects to an unknown degree. (The 125gr EPR bullet developed for 6.5 CT ammo has a very long base, which would reduce powder capacity if loaded into the 6.5 Grendel case, adversely affecting muzzle velocity.)