Grendel as a Universal Infantry Cartridge

[JASmith]

...You are using data based off of a 123 Lapua Scenar match grade bullet in comparison with M-80. Two different animals with huge differences in quality and particularly cost...Reduce it to a rational ball round and then things change real fast.

LR55,

We've had this discussion before -- and, except for the M855 experience, I do not have data to suggest a more optimistic ballistic coefficient than you suggest. So, incorporating the "more mundane" ballistic coefficients is why the "Battle Rifle Cartridge" study listed above suggests that the Grendel is a little shy of being good enough by the standards of that discussion. The "6.5 mm and the Politics of Procurement" discussion uses the Scenar and and is looking at a full-length cartridge, so the service that adopts it would need to do a more-or-less complete replacement of infantry firearms. These folks are somewhat more optimistic with their views on realizable ballistic coefficients and their consensus is that a BC of about .52 might be attainable in a production 8 gram (123 grain) bullet. BTW, it looks like one would need 40-44 grains water capacity to get the desired 800 meter/second muzzle velocity in a 20" barrel.

So far, I tend to agree with RFB and my view has always been that the Army can design a bullet for the 5.56 that is more lethal on humans if the Army wants to.

The M855-A1 claims to do that. I am curious about how well this round fulfills the promise and what its ballistic coefficient is.

A question though. Why the 1100 meter lethality range? I mean, what is the rationale for that distance?

Ah.. this is one of the challenges of referring to three different studies to inform a debate. They each have different objectives and constraints. The 1100 meter requirement is from the discussion in Tony William's "6.5 and the Politics of Procurement" discussion. Here the desire is to replace both cartridges with a single ammunition type for the roles up to and including the GPMG. Further, the thought is that the cartridge must be demonstrably equivalent to the M80 in terms of penetration and lethality at 1100 meters.

--Joe