(06-03-2023, 04:49 AM)p358 Wrote: IMHO the only and quite sensible reason to move away from 5.56 is to get enough firepower to penetrate a vest.
5.56 is useless for this role.
So ... will this cartridge / weapon combination or whatever they end up using, kill through a vest?
I have never liked the 5.56 for this reason.
P
I don't think the 5.56 was ever meant to be a primarily killing round. Instead, it was meant to incapacitate. When you incapacitate an opponent, you take him out of the fight of course, but additionally you take, on average, two more combatants out of the fight, because someone has to care for the wounded and haul them out of the line of fire. If you simply kill him, his cohorts tend to just leave the carcass laying for later retrieval and keep coming at you.
In the early '80's, the USMC insisted on trying to make the 5.56 more lethal, and that led to the Belgian SS109/US M855 round, with increased weight, increased stability, and in theory more lethality, as the mild steel core penetrator was supposed to punch through armor better. The net result of that was to actually create a LESS lethal round, as was discovered by our troops on Somalia. The heavier weight and steel core did do their job of increasing penetration, but over-stabilizing the round led to smaller wound channels, and we found that shooting a Skinny just punched a neat hole right through them, with the net result that they would keep coming at you, failing to realize that they were supposed to be dead.
Then body armor penetration resistance was just increased to stop what penetration they had gained, negating it. That same phenomena will happen for any round they can develop to increase penetration - someone will come along with better armor to stop that. Because of that, armor has to be worked around - if you want to simply kill them, work for head shots, and if you'd prefer to take advantage of the 3-for-one deal, arms and legs have to be damaged... but the ol' "center punching" is not something to aspire towards in the Age of Armor.
Penetration can be a good thing, but they turned the round into TOO MUCH of a "good thing", in my opinion. It hasn't been quite right since the conversion from M193 rounds to M855 rounds.
ETA: Like I said, I'm an Old Guy, so I prefer the M193 concept - higher velocity due to lower weight, and less stability, creating more horrific wound channels. The problem with using it in this day and age is that it is nearly impossible to find a barrel with the correct rifling twist for it. 55 gr M193 is optimized with a twist of 1:14 to 1:12, but 62 gr M855 is optimized for stability at a twist of about 1:7. I have a cache of both M193 and M855, and my own AR has a twist rate of 1:9, to "optimize" for both, but the net result is that it is perfect for neither, just an attempt to be able to use either and be "close enough for government work".
.