05-04-2011, 08:46 PM
JASmith Wrote:LRRPF52,
Thanks for the excellent clarification!
Your discussion helps sharpen my thinking! I lean toward finding a cartridge that can take the near-muzzle lethality of the M855 and push that lethality level out to slightly beyond where one can reasonably expect to get reliable hits. For some, that range is about 7 meters, for others it is much further, but enough folks would like to see 400-500 meters that this makes a good starting point for discussions.
There's a lot in terminal effects on humans and real-world barriers that we just can't accurately model. That's why I try to use metrics like momentum and energy density coupled with a reasonable lethality metric. My favorite is the product of the bullet mass and the bullet momentum density to give a measure of penetration depth (momentum density) and material available to create a permanent wound channel (the mass part of the expression).
The bullet design is also important, but the critical first step is to assure that it has the right combination of mass and velocity so that the design can work!
Anecdotal observations like yours go a long way toward anchoring the though processes. Thanks again!
JASmith,
All I know is that when I pick up an M4 or AR in 5.56, I have respect for the capacity it has to do some seriously ugly damage or lethality, especially if using thin-jacketed M193 and M855 or similar loads on the hotter end of the scale. Most soldiers are not able to make 400m hits with RDS-equipped sticks in a dynamic scenario with stress, which is why belt-fed weapons and Designated Marksmen or Sniper Teams shine at those distances. What I saw over several different light infantry units was that only about 25-50% of Infantry soldiers could reliably make the 300m hits on the standard qualification range in fairly stress-free conditions with recently-zeroed weapons in sunny weather and fresh chow in their guts.
Maybe magnified optics increases that hit probability, but we were using Elcans on the M240's and SAWs back then, which worked out well, except for the weight. I saw guys in Ranger Regiment who would mount 4x ACOG's on the 240's, which is a much lighter solution than the M145 Elcan. I just start to naturally lean to discussing belt-fed weapons again without even intending to when we talk about those distances, unless we're talking about DM's and Sniper Teams, which usually located themselves with the support-by-fire position where the 240's were located for planned attacks at the Platoon or higher level. If I had not spent 10 years with dismounted Infantry and Airborne units, I think my posts would look entirely different than they do, focusing more on the caliber solution, versus a holistic solution that includes training and employment, weapons, equipment, doctrine, procurement, RDT&E, mindset, etc. That is not meant to distract from the equipment/weapons portion of the solution in any way, but it helps to have the context in mind that these weapons will be employed in before jumping the gun. I just wish we could be testing a Grendel LMG right now...
LRRPF52