Testing, testing...

[stanc]

The range is the hiccup. Remember that most folks carrying M-4's have a far greater chance of engaging targets well under 300 meters. One would think that relevant testing at these shorter ranges is in order.

I agree that testing at shorter ranges is a good idea. That's why the first iteration of the Infantry Rifle test called for target distances as close as 25 yards. However, hit probability of any assault rifle cartridge -- especially the low-recoil 5.56x45 -- will be good at close range.

I changed the range requirement to longer distances, primarily because of the reported complaints from troops in Afghanistan that 5.56 lacked sufficient reach to engage an enemy who 50% of the time attacks from as far away as 1000 yards. I think it's more important to determine if 6.5 Grendel would answer that complaint, and if so, how well.

Accuracy isn't the principal issue for these shorter range tests, but bullet performance is.

Concur. But, we don't have access to 5.56 M855A1 ammo, and AFAIK, neither an M855-type nor an M855A1-type bullet exists for 6.5 Grendel. So what 5.56 and 6.5 loads would you use to compare terminal performance?

The spirit of the test regime, especially with the cinder block and milk jug protocol, suggests that plywood and water jugs could readily be used behind something that resembles a windshield or door frame.

True. And there are other "witness pack" possibilities, as shown in a couple of NDIA presentations by Gandy and Arvidsson. But, again -- what 5.56 and 6.5 loads would you use to compare terminal performance?

While no amount of testing by us amateurs can hope to duplicate, let alone supersede, formal military acceptance testing, poorly defined and designed tests can do an awful lot of harm.

Well, if you consider my proposed tests to be poorly designed, then propose some of your own.

Remember, our goal is to encourage analysis and testing by the service acquisition community.

Agreed.

We need to posit a hypothesis like "The 6.5 Grendel can replace both the 5.56 and 7.62 mm NATO ammunition types." and then build the analytical case that shows that, given demonstrated ammunition performance, the hypothesis is proven.

Yes, but to date all we have is theory and supposition behind that hypothesis. There needs to be empirical evidence, which can only be had via testing.