IMHO, the leading edge has always been Russian
armaments. They've discarded more better, original
designs in a decade than we see in a century.
Not that I personally prefer it, but the AN94
is hard to beat, for one...
While we were futzing around with the M14's dubious
evolution, they shelved over a dozen separate, new,
functional, potentially superior designs to the AKM because they
had a strong infantry weapon, and felt, overall, that "the
perfect(better? DNK Russian) is the enemy of the good".
American weapons and associated electronics have also
made the G3, while still state-of-the-art, obsolete as a
"leading edge" weapon.
(You did ask...)