Re: Terminal effects of 5.56
Everyone should agree that all that matters is "does it put the target down".
The smallest bullet that puts the target down reliably is optimal.
Minimal recoil is important for marksmanship and getting rounds on target quickly.
New shooters do better with light recoiling, smaller, lighter rifles.
Light ammunition has obvious benefits.
The early M-16's had 1:14 twist barrels and produced (reportedly) devastating wounds with 55 grain FMJ.
Bullet stability was marginal so the twist was upped to 1:12.
The "out of all proportion" wounding was reduced but practical bullet accuracy improved.
Longer bullets are easier to get to tumble, and being longer, they should produce more drag whilst sideways.
I'd bet that the lethality of the M855 would increase if it was shot out of a 1:10 or even a 1:9 and given a deeper cannelure.
The tracer is (I believe) the reason for the 1:7 twist.
It's a long bullet of dubious merit, especially in an AR type rifle.
If we could squeeze 80 A-maxes into a magazine (we can with wildcats) it would probably bring back the devastating wounds that the early M193 enjoyed out of the 1:14 barrels.
http://www.6mmar.com/224_AR.html
The practical range would increase and the bullet would have more energy than Mk 262 at all distances.
The .224 AR has over 500 ft x lbs. at 600 yards and good to >1000 yards in a 16" carbine.
It hits harder at 1000 yards than the 62 grainer does at 600, and with only 18 grains more bullet, 3 grains more propellant, and a few grains more brass.
It is more efficient IMO.
Everyone is after the "holy grail" of calibers but they are all a compromise of sorts.
Improving external ballistic efficiency is (IMO) what should be focused on.
If we want the round to hit harder at distance we should feed it bullets that waste energy slower in the air so the target can get more.
Spin those longer bullets enough to get there, but not a lot more.
This allows the bullet to "Ice pick" if it's an FMJ and it will also tumble far easier based solely on it's length.
One way to satisfy the armor penetration requirement along with the antipersonnel requirement and the Geneva unconvention all at the same time.
The energy to do the work has always been there with the 5.56.
Getting it dissipated into the target at engagement ranges has been an issue.
Efficiency improvements and terminal ballistic design will only make it get better and, for now, it's good enough.
I've met a person who'd been hit with the 7.62 x 39 four times.
(Twice in the lower back)
It seems to penetrate very well but based on his injuries I suspect that most of the energy passed right through him.
The exit wounds were old but based on the scarring I'd have to say that the bullet wasn't tumbling.
At shorter ranges the 7.62 x 39 has more energy and more caliber than the lowly 5.56 so why does it seem to underperform?
It's in the details.
This is presented as opinion and that is all.