Actually outside of Vietnam where the 5.56mm was introduced the smaller round was superior to the 7.62mm against body armor given the rounds
tendancy to tumble. In fact the Soviets designed the AK-74 with a smaller 5.45mm round for that very reason.
5.56 was designed for small game hunting, it was not designed as a military round. It was in fact redesigned and adopted for military use as a
defense LOS only caliber.
The reason Soviets designed their own small caliber round was do to economics. It was CHEAPER to crank out 5.45s and it also increased ammo load for
the troops. Considering the sheer size/structure of their motorized infantry divisions, they decided that high penetration round will not be
necessary do to available MG support, so LOS round was deemed as acceptable.
Soviet troops in Afghanistan disagree with that notion, and convoy troops were regularly forced to "borrow" AKMS type that truck drivers had in
their rigs.
Round fragmentation has nothing to do with body armor penetration. Level III is supposed to stop a 148gr 7.62 round at 2750 f/s. The problem is that
not all 7.62 rounds are created equal. While various soft core hunting rounds are stopped, mil spec steel cores are not.
Such steel cores are not designed to have AP capability, they are made from stamped steel like 65G and hardened to 65HRC. AP cores are made from high
carbon U12A steel.
Soft body armor does not stop steel core rounds. The jacketing peels of and the core continues to travel through the target. That's where the core
caliber plays a decisive role.
This is where Level IV comes in. Armor plates are designed to stop all steel core rounds and AP rounds up to 166gr with minimum velocity of
2850f/s.
That includes 7N23 and 7N22. Unfortunately they have repeatedly proved to go through 16mm armor plates like through butter.
Further more, modern non-AP "enchanted penetration" rounds defeat 10mm APC grade armor from 100m with 100% success rate.
Level IV plates simply don't stand a chance against a square hit, high angle deflection shots, sure.
What new rifles? The XM8 WAS the new rifle. They only produced a few prototypes and they probably either put them into storage or destroyed
them.
Nope, it's a "restyled" G36.
My favorite for replacing the M-4/M-16 would be the M468 Barrett.
And who's supposed to pay 2,500 dollars per copy? Let me put it this way, considering the type of folks those guns are supposed to be used against,
I garantee you, instead of trying to shoot them, just give them $2500 each and the war is over.
Considering caliber/configuration options SCAR would be a definite improvement.